Much of what you'll hear today is based on James Comey's notes. He described in his advance testimony that he decided to begin taking contemporaneous notes of his meetings with Trump after becoming uncomfortable with the president's requests.

The FBI director began typing the notes in his car the moment he left Trump Tower and later the White House. He said he saw no need to take notes of the two occasions when he met Barack Obama.

Although they cannot be corroborated, contemporaneous notes taken by an FBI agent would hold up in court as credible evidence of conversations, so Comey's account is likely to be taken at face value today at the Senate.

"Contemporaneous" ("existing, occurring, or originating during the same time") was one of the most searched words on the Merriam Webster online dictionary on the day news reports about the meetings emerged.

Image source, Getty

James Comey's prepared testimony describes a series of one-on-one meetings in which the president said he needed loyalty from the then-FBI director and appeared to ask him to drop an investigation into former National Security Adviser Michael Flynn's alleged ties to Russia.

We knew about this request already, it was detailed a fortnight ago in an article by a lawyer and friend of the former FBI director. Comey's testimony could add weight to the issue, in that he will say publicly for the first time that he construed the remark as a specific request to drop the Flynn inquiry:

Law professors told the BBC when the remarks were first published that they did not add up to a smoking gun, and Comey offering his interpretation in front of the Senate is unlikely to change that.

You can read more on the obstruction of justice issue here.

Speaking to the BBC this morning, Republican senator Lindsay Graham said accusations of obstruction were "not helpful to the president".

A lot of bars are hosting special events to mark the hearing.

The Union Pub on Washington's Capitol Hill is pledging to give out drinks every time the president tweets.

A bartender at Clooney's Pub in San Francisco told the BBC: "We've been getting so many calls and people have been asking to make reservations. [They're asking] 'Can I get a seat? 'Are you serving breakfast?' I was like, 'You guys, it's a Thursday morning.'"

Some places have also promised covfefe cocktails, inspired by the president's infamous typo.

You can read more about the barroom build-up here.

Image source, Getty Images

Virginia Democrat Mark Warner, who serves as vice-chair of the committee, has released his prepared opening remarks.

Comey's testimony is "disturbing", he will say.

"I do want to emphasise what is happening here - the president of the United States is asking the FBI Director to drop an ongoing investigation into the president's former national security adviser," Warner is expected to say.

Warner plans to say that these efforts by Trump are "not how a president of the United States behaves".

"Regardless of the outcome of our investigation into those Russia links, Director Comey's firing and his testimony raise separate and troubling questions that we must get to the bottom of," he will say.

Comey departed his home in the suburbs of Washington DC in a gold-coloured SUV at 8:54 local time, according to reporters camped outside his home.

Who says only British people like queuing?

The BBC's Rajini Vaidyanathan , externalhas arrived in the committee room, where some eager young Senate staffers have lined up since 04:00 this morning to grab a seat.

Trump's critics are charging him with obstruction of justice for his alleged pressure on Comey to pledge loyalty and drop the Michel Flynn investigation, which the president has denied.

Not so fast, South Carolina Senator Lindsey Graham tells the BBC.

Mark Warner, Virginia, Vice-Chairman - Comey's incoming testimony is "disturbing", he will say in his opening remarks, adding that is "not how a president of the United States behaves"

Dianne Feinstein, California - Trump called her before firing Comey, but the reason he gave turned out to be different than what he told the public, she says

Ron Wyden, Oregon - If Trump asked for the Flynn investigation to be dropped then that"by itself is almost a Watergate-level effort" to interfere with an ongoing investigation

Martin Heinrich, New Mexico - Yesterday he slammed Trump's intelligence chiefs, for refusing to answer whether Trump asked for the Flynn investigation to be dropped

Angus King, Maine - If Trump asked for the Flynn investigation to be cancelled it would be an impeachable offence "because obstruction of justice is such a serious offence"

Joe Manchin, West Virginia - He is one of the few Democrats to at times praise the president, saying that as a moderate, "I have access, I can speak to him"

Kamala Harris, California- The former prosecutor is fond of grilling Trump’s nominees during their confirmations, and has voted to oppose 18 of them from joining the White House

Image source, Getty Images

Richard Burr, North Carolina, Chairman - He has promised a non-partisan investigation into Russian hacking in the 2016 election, and was critical of Trump's firing of Comey

Jim Risch, Idaho - The real issue, he believes, is government leakers, whom he has described as "traitors" and "weasels"

Marco Rubio, Florida - "Little Marco", as Trump derided him, seems to have buried the hatchet with his old nemesis, and dined with the president just two days ago

Susan Collins, Maine - She hopes today will help "determine the facts of the Russian involvement in our elections last fall"

Roy Blunt, Missouri - "Let's find out what happened and bring this to a conclusion"

James Lankford, Oklahoma - He says Comey's testimony on Trump's loyalty pledge "sounds exactly like [how] the president spoke to every other Cabinet official"

Tom Cotton, Arkansas - Trump should focus more on enacting his agenda and less "on all of the hair-on-fire, wild-eyed allegations" about Russia ties

John Cornyn, Texas - "I've heard what I think is a phony narrative that he [fired Comey] to somehow to squelch the investigation into Russia, which I don't believe there's any evidence of"

Image source, AFP

With an hour to go, Comey is leaving his home in McLean, Virginia, to make the 13-mile journey to Capitol Hill.

The internet, meanwhile, has been having some fun with his prepared remarks.

You can peruse them here, external.

It's a rip-roaring read.

James Comey’s seven pages of prepared testimony landed with a thud on news desks across this nation yesterday, sending cable networks into a tailspin with talk of Russian hookers, awkward silences and a grandfather clock. There’s currently a queue snaking down the corridor outside the Senate Intelligence Committee as the former FBI director prepares to take centre stage for what is being likened to a political Super Bowl. He's sworn in at 10:00 local time (14:00 GMT).

Image source, EPA