That's it from us for today.

To recap, House Democrats have opened arguments in the Trump impeachment trial.

Adam Schiff urged Republican senators to join them in voting to remove Trump from office to "protect our democracy".

He warned that senators would "also undermine our global standing" if they do not oust the Republican president.

Attending the World Economic Forum in Davos, Switzerland, Trump jokingly warned he might confront Democrats by coming to "sit right in the front row and stare at their corrupt faces".

Democrats have up to three days to make their case.

Trump's defence team will have three days after that for rebuttal.

The trial could conclude as soon as next week.

Image source, Reuters

Image source, Pew Research Center

Just as the Senate trial gets underway, slightly more Americans say that President Trump should be removed from office, according to the latest poll from Pew Research Center.

51% of Americans say the president should be removed by the Senate trial, while 46% say Trump should stay.

These results are starkly divided along partisan lines: 85% of Democrats think Trump should be kicked out while 86% of Republican voters think he should stay.

The country is more united when it comes to Trump's alleged wrongdoing.

63% of Americans say Trump has "definitely" or "probably" done something illegal.

An even larger majority - 70% - say he has "definitely" or "probably" done something unethical.

Joel Gunter
BBC News, at the trial

By late afternoon, some senators in the chamber had begun to look like the long hours of detailed evidence were taking their toll.

Sylvia Garcia, a Texas congresswoman and Democratic impeachment manager, was walking senators through the movements of various players in the Ukraine scandal, interspersing her prepared statement with audio and video clips.

It's a convoluted story to follow, even for those already familiar. And there is a lot more evidence to get through - the Democratic House managers laid out their case slowly and meticulously today, as they did yesterday.

The brief they submitted before the trial was more than 100 pages of heavily footnoted evidence. By contrast, the president's team submitted seven pages, with no references. The defence will begin its oral arguments on Saturday.

If witnesses and new evidence are admitted, senators may sit through these sessions for several more weeks.

They are allowed only water and milk - no coffee - to keep them going, and the occasional piece of chocolate from the bipartisan Senate confectionery draw.

So young staffers ferry glasses of water constantly around the chamber. Plus one glass of milk, while I was inside, for the Republican Senator Tom Cotton.

During the recess, Democratic leader Chuck Schumer approached microphones only to find that top Republican John Cornyn was already being interviewed.

So he waited patiently for his turn.

When Cornyn made a remark about witnesses testifying to Congress, Schumer chimed in to say he agrees. Yup, you read that right - a top Democrat concurred with a top Republican.

Congress may be bitterly split over impeachment, but it seems the two parties in the upper chamber can occasionally agree on something.

Joel Gunter
BBC Journalist, World

Image source, Getty Images

Long-serving Democratic senator from Delaware Tom Carper spoke to the BBC's Joel Gunter during a recess, to discuss what the atmosphere was like in the chamber amid a deeply partisan process.

"A lot of people think we just fight in the Senate and in the House, but we are actually friends for the most part. It's a friendly atmosphere," he said.

"As I sat there today listening to Senator Schiff speak, for a long time, I was impressed - the members didn't start reading, or talking, they weren't sitting smiling or rolling their eyes. They were intent."

The Senate sat in session for 12 hours last night. Senator Carper said he held his concentration by writing hourly summaries of the testimony in his journal. "I felt stronger as the night wore on. Somebody asked me, 'What are you on?' I said, 'I'm on Democracy!"

Democratic Senator Chuck Schumer is shooting down suggestions that a witness swap will take place to allow Democrats to get a witness to testify in exchange for a Republican-picked witness.

Democrats hope to get former US National Security Adviser John Bolton into the witness chair, while Republicans want to speak to the son of former US Vice-President Joe Biden, Hunter Biden, whose work for a Ukrainian energy firm spawned accusations of corruption from Trump and his allies.

"Witnesses should have something to do with and direct knowledge of the charges against the president," said Schumer, referring to rumours of "witness reciprocity".

"You know, we don’t need to have witnesses that have nothing to do with this that are trying to distract Americans from the truth."

Louisiana Republican Bill Cassidy has warned Fox News viewers to beware of people throwing "monkey dust... trying to distract from what is the crux of the issue".

"If we look at the crux and remain focused on that crux, then we'll establish whether the president did something illegal or not."

It's unclear whether Cassidy, a medical doctor, is aware that "monkey dust" is also the street name for an illegal synthetic drug (methylenedioxypyrovalerone) that is also known as "bath salts".

Jon Sopel
BBC North America Editor

Why is Trump weighing in from Switzerland?

There was one thing in particular that Trump said which was kind of like a red rag to a bull.

It's when he said basically: "Well things are going very well, we have all the information, and they [Democrats] have none of it."

Well, if you want a fair trial, then maybe that information should be made available.

We keep using the word "trial", and the words "jurors" and "witnesses" and "evidence", but we must not lose sight that this is a political process.

We saw that clearly last night when the first votes started coming in. In a vote that split completely along party lines, 53 Republicans said "no we should not be able to subpoena the White House for documents", while 47 Democrats said "yes we should".

So we have Donald Trump kind of goading and saying: "Look I've got the information. We know what happened, but we're not going to tell you."

I think this might inflame public opinion. Polls are already indicating that a clear majority believe that evidence should be handed over and witnesses should be called.

Are journalists overstating the significance of all this?

Politicians always over-estimate the extent to which the general public are paying attention to their words.

It is a condition not unique to the United States of America. It is a global phenomenon that whatever politicians say, they think the public will find tremendously important and fantastically interesting.

But, amazingly, members of the public are getting on with their lives.

That is an important thing to bear in mind. Some of us - obsessive forlorn political journalists like me - are watching in immense detail, while other people are just getting on with it.

Some people will be watching this for its historical important. But for the overwhelming majority of Americans, I expect there to be just a few fleeting moments of attention paid to the serious discussion taking place in Washington.

It doesn't seem to be changing the lives, or minds, of the American people all that much.

Lead impeachment manager Adam Schiff, representing Democrats, has just wrapped up about 2.5 hours of opening arguments, leading to Leader Mitch McConnell to announce a short recess.

"If we don't stand up to this peril today, we will write the history of our decline with our own hand," he warned the senators who will serve as Trump's jury.

Meanwhile, Trump has tweeted in reference to his July call with the Ukrainian leader.

"NO PRESSURE" Trump wrote, referring to the Ukrainian president's statement that he did not feel pressured to open political investigations into Trump's domestic opponent Joe Biden, in exchange for the unfreezing of US military aid.

A letter signed by 21 Republican state attorneys general and released on Wednesday argues that impeachment "threatens all future elections and establishes a dangerous historical precedent" for US politics.

"That new precedent will erode the separation of powers shared by the executive and legislative branches by subjugating future Presidents to the whims of the majority opposition party in the House of Representatives," wrote the top lawmen of 21 states.

They claim the abuse of power charge "is based upon a constitutionally-flawed theory" that is "infinitely expansive and subjective" because it is based on the president's alleged motivations.

They say the other charge - obstructing justice - is "equally flawed" because it would render executive privilege "meaningless".

"Impeachment should never be a partisan response to one party losing a presidential election,” the 14-page letter says. "If successful, an impeachment proceeding nullifies the votes of millions of citizens."

The only Republican attorneys general not to sign the letter come from Arizona, Idaho, New Hampshire, North Dakota, South Carolina, Utah and Wyoming

Image source, Getty Images

In his opening remarks, lead impeachment manager Adam Schiff kept mentioning Founding Father Alexander Hamilton.

But what does Hamilton - the first US treasury secretary and now the subject of an award-winning musical - have to do with Donald Trump's impeachment?

Hamilton penned the two essays devoted to impeachment in the Federalist papers. Hamilton wrote that a political impeachment trial is different to a criminal trial.

In other words, an illegal act is not required for impeachment.

"Hamilton seems to have predicted the rise of Donald Trump with staggering prescience," Schiff said.

Joel Gunter
BBC Journalist

Adam Schiff began his opening remarks by sombrely quoting Alexander Hamilton: "When a man unprincipled in private life desperate in his fortune, bold in his temper, possessed of considerable talents... When such a man is seen to mount the hobby horse of popularity - to join in the cry of danger to liberty..."

Though the president was not in the dock, the target of Schiff's history lesson was impossible to miss.

The Democratic congressman went on to rehearse the impeachment managers' arguments against President Trump, from the scandal with Russia to the Hunter Biden business in Ukraine.

Senate majority leader Mitch McConnell sat still, fixing an unbroken glare on Schiff.

No desk in the Senate chamber was empty. All the Senate Democratic presidential candidates were there - Amy Klobuchar took notes; Elizabeth Warren sat upright, attentively; Bernie Sanders sat low in his seat, yawning occasionally and holding his head in his hands; and Michael Bennet was there, too.

Schiff returned to Alexander Hamilton later in his remarks, saying Trump had "acted precisely as Hamilton and his contemporaries had feared" when they framed the remedy of impeachment. He implored the gathered senators to act impartially.

"It is up to you to be the tribunal that Hamilton envisioned," he said. He quoted John F Kennedy: "With a good conscience our only sure reward, with history the final judge of our deeds..."

The senior Republican senators showed no reaction.

President Donald Trump is accused of an abuse of power and obstructing Congress and most believe it's a foregone conclusion that Trump will be acquitted at the end of this process, because his party controls the Senate.

But could the trial go off script? The BBC's Anthony Zurcher and Shrai Popat take a front-row seat.

Senators were just warned that they are "commanded to keep silence, on pain of imprisonment," but quite a few say they will find it rather difficult to abide by the stringent rules

"Every senator will have some trouble - we are not, by nature, silent," Missouri Republican Senator Roy Blunt told the New York Times, external. "The desire to hear the sound of your own voice will be frustrated by that rule."

In addition to the vow of silence, senators are also banned from using cell phones and are required to leave them outside the chamber in cubbies.

In a possible violation of the rules, several senators have been seen wearing smartwatches.

After Senator Ted Cruz was criticised because his official Twitter account continued posting during Tuesday's hearing, his team posted a cartoon of a cell phone with the caption "come and take it".

That slogan is popularly used by gun rights activists, but it actually originates in the 1835 Battle of Gonzales that took place during the Texas Revolution.

Montana Democrat Jon Tester, a farmer, is no friend to technology and says he welcomes the break from mobile distractions.

"I sit on a tractor for 18 hours a day and my cellphone doesn’t work - this is like heaven to me," he told the Times.

"I think it’s going to be really interesting, and not having a cellphone is like - that’s my dream job," he said before adding: "The truth is, this is serious business."

A Monmouth University poll released this week shows that a majority of the country thinks the trial should allow new evidence, but that support is deeply partisan.

Here are the key stats:

• 57% say the House managers should be able to present new evidence

• Support for allowing new evidence comes from 87% of Democrats, 56% of independents, and just 24% of Republicans
• More than 3 in 4 Americans say Trump and his officials should be invited to testify, but only 40% think Trump should be compelled to testify
• 53% approve of the House of Representatives decision to impeach Trump, while 46% disapprove
• 49% feel Trump should be removed while 48% say Trump should not be removed

Image source, Getty Images

Lead impeachment manager, Democrat Adam Schiff lays out the timeline of events leading to Trump's impeachment.

Schiff has emphasised Trump's "infamous" 25 July phone call with Ukrainian president Volodymyr Zelensky - at the centre of today's trial.

So what's he talking about?

A rough transcript of this conversation, released in September, revealed Trump had urged President Zelensky to investigate former US Vice-President Joe Biden, the front-runner to take on Trump in the 2020 election, as well as Mr Biden's son, who held a board position with a Ukrainian gas firm.

Just 91 minutes after this phone call, the White House sought to freeze aid to Ukraine, a newly disclosed government email suggested last month.

Democrats argue that the $391m (£316m) in military aid temporarily blocked to Ukraine is proof of Trump's abuse of office.

Image source, Reuters

House Intelligence Chairman Adam Schiff begins by thanking senators for their "patience" in listening to arguments until 2am local time on Wednesday.

He then quotes US Founding Father Alexander Hamilton about the need for impeachment as a mechanism to remove "a despot" from office.

"They did not intend for the matter of impeachment to be used frequently or as a matter of policy," he says, but it was put in the constitution "for a reason".

The writers of the constitution, he said, "devised a remedy as powerful as the evil it was meant to combat - impeachment".

In a clear reference to Trump, he said the impeachment clause was placed there for "a man who would would seek to subvert the interests of the nation, a man who would... seek office by cheating at an election."

Republican Lindsey Graham, one of Trump's most stalwart allies in the Senate, has just held a press conference to slam Democrats for holding impeachment proceedings so close to November's presidential election.

He accused them of working against the will of the American people.

"I wouldn't give them the time of day," said the South Carolina senator. "They're on a crusade to destroy this man!"

He added: "When it comes to replacing this president nine months plus from the election, you got an uphill battle with me."