Ritu Prasad
BBC News writer, Fort Myers, Florida

We’ve been asking our readers for their most pressing questions about the US election. Now it’s our turn to respond.

Click here if you want to know more about this project or send in a question of your own.

Kin Choong Leong, 62, from Petaling Jaya, Malaysia, asks: How are the subjects of the debate chosen?

The whole debate season is governed by the aptly named Commission on Presidential Debates, a nonprofit group founded in 1987. The Commission selects the moderators and the moderators pick what subjects the candidates will debate.

The moderators do not share the specific questions with anyone, but they reveal the general topics a week before the event.

How are these moderators chosen?

According to the Commission, external, they focus on three criteria: familiarity with the campaign and candidates, live broadcast news experience, and “an understanding” that the debates must focus on the candidates and their views.

Image source, Getty Images

The widow of a former St Louis police officer is among Pence's guests tonight, according to the White House.

Ann Dorn's husband, David, was killed during protests in the wake of the death of George Floyd - a black man who was killed in police custody.

Her inclusion on the guest list indicates that Pence plans to attack Harris' support for the Black Lives Matter protests. The majority of those protests have been non-violent but some have devolved into clashes between police and rioters, looting, vandalism and crime.

Violent crime rates have been rising in many cities under the Trump presidency. The Trump and Biden campaign have clashed over who is to blame - Democrats who run many of the city governments or the Republicans in Washington who control the federal government.

Sophie Long
BBC News, Salt Lake City

The two campaigns had what you might call a pre-debate debate over the plexiglass on stage tonight... Pence's campaign had resisted that, possibly because this is not just about safety and about a pandemic of course, but also about the politics and the visuals of the night.

The 90-minute debate will be watched by tens of millions of people across America and beyond, and there will be those glass barriers visible throughout as a sign this is taking place in the middle of a global pandemic, one that has killed more than 211,000 Americans.

And of course, one of the people on the stage - Mike Pence - has been leading the task force co-ordinating the Trump administration's response.

Former Arizona Republican Senator Jeff Flake has been telling BBC Newsnight what he thinks we can expect from tonight, saying vice-presidents typically don't talk about their own policies, but those of "the person at the top of the ticket".

The vice-president will have his work cut out for him, it seems.

Mike Pence "will be forced to defend some of those things - he'll try to deflect," Flake suggests, "but there is really no defence for some of the behaviour of the president in the last week."

We've got just under an hour to go, so we hope you've prepped some dinner and/or snacks! We'll keep you covered with more analysis and news as the night unfolds.

And a reminder that when the clock strikes debate hour, you can stay with us and watch the event online, or on BBC World TV around the world and on the BBC News Channel in the UK.

The BBC's Ron Brown has been driving around near the debate venue and has sent us some clips of what is going on. He just passed a big pro Biden-Harris gathering by the roadside about a mile from venue, and has seen what he describes as a "pro-Trump" firetruck bedecked with American flags.

Image source, Getty Images

Trump's campaign has cheekily set aside a seat for the late West Coast rapper Tupac Shakur, after Harris named him as her favourite artist.

"We have left a ticket for Tupac Shakur," Trump's senior campaign adviser Jason Miller told reporters on a conference call on Wednesday.

"I'm personally more of a Biggie fan," said Miller, referring to the New York rapper Notorious B.I.G. with whom Tupac feuded.

The stunt is a reference to Harris' statement last month at a charity event that Tupac is her favourite living rapper. She had to be reminded by the moderator that Shakur, who went by the stage name 2Pac, died in 1996.

Salt Lake Tribune reporter Brian Schott has tweeted pictures of a commemorative coin that could be worth a pretty penny to presidential memorabilia collectors someday.

It shows tonight's date, the name of the debate venue, and one side is blue for Democrats and the other red for Republicans.

Official memorabilia for debates past have included beer pint glasses, pens and thermos bottles.

It's Mike Pence's night, but Donald Trump is certainly making his presence felt on Twitter.

Following on from a video message in which he called catching Covid-19 "a blessing from God", the president has now pledged to pull the last American troops out of Afghanistan.

Whether that really means every last one is unclear. Earlier today, National Security Adviser Robert O'Brien said the US would go down to 2,500 troops in Afghanistan in early 2021.

Last week's debate between President Trump and his challenger Joe Biden pulled in some 73 million TV viewers - but we can probably expect a lower number for tonight.

It's no reflection on the lure of Mike Pence and Kamala Harris, since the VP debate has drawn lower ratings most years since the mid-1970s.

During the 2016 election, 37 million people watched Mike Pence (then governor of Indiana) debate Senator Tim Kaine - an audience 44% smaller than the least-watched Clinton-Trump presidential debate.

There was one exception, though: Joe Biden and then-Alaska Governor Sarah Palin in 2008. An impressive 69.9 million tuned in - more than for any of the presidential debates between candidates Barack Obama and John McCain.

Image source, Reuters

Image source, Getty Images

USA Today's Washington bureau chief Susan Page will be in charge of the debate tonight, and she'll be hoping for an easier ride than the one Chris Wallace got last week. The 69-year-old Kansas native joined the fabled national paper in 1995 after working at Newsday, a popular New York paper.

Page is a seasoned operator, with ten presidential campaigns under her belt. She's interviewed the last nine presidents, and she won't be intimidated by the occasion.

Away from the newsroom, she's written a biography of former first lady Barbara Bush, and signed a book deal in 2019 to chronicle the life and career of House Speaker Nancy Pelosi. She's a regular pundit on US cable news shows, and was once president of the Gridiron Club, one of Washington's oldest and most prestigious journalistic societies.

Read more: What to look for in vice-presidential debate

Mike Pence has taken the traditional off-camera tour of the debate stage ahead of the event tonight at the University of Utah's Kingsbury Hall.

After staying there for 45 minutes with his wife, Karen Pence, he is now awaiting the start of the debate at the Hotel Monaco, where he is staying with his family.

Image source, Getty Images

Vice-presidential debates rarely loom large in election years, but when they're remembered, it's often for their gaffes.

An embarrassing put-down for Indiana Senator Dan Quayle, George HW Bush's 1988 running mate, is still quoted.

During the debate against Democrat Lloyd Bentsen, Quayle was asked if he thought he was qualified to be vice-president, being only 41 and having limited political experience.

He answered, fatefully: "I have as much experience... as Jack Kennedy did when he sought the presidency."

Bentsen's retort was blunt and brutal: "Senator, I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine. Senator, you are no Jack Kennedy."

The retort, coupled with the stunned look on Quayle's face, sent the Republican campaign on to the defensive and they spent weeks trying to rehabilitate his image.

Of course, they still won the election - but "you are no Jack Kennedy" remains the most memorable line from a VP debate to live on in the American political psyche.

Image source, Getty Images

In picking veteran politician Mike Pence as his vice-president in 2016, Donald Trump went with a safe choice who would help secure him the evangelical Christian vote.

"A Christian, a conservative and a Republican, in that order" is how Pence once described himself.

In the last three years, you could say he's added loyal Trump soldier to that list.

The vice-president has made it his mission to be a faithful and unprovocative lieutenant, but we've taken a look at the few times the vice-president didn't stay out of the limelight.

Mike Pence: The rare times he made headlines

She's made history as the first black and Asian woman on a major US party ticket. But what are her views? Even President Donald Trump and his Republican allies seem undecided about how to define the California senator ahead of the 3 November election.

Kamala Harris: Where does she stand on key issues?

Image source, Getty Images

Welcome! We've got two hours yet to go before the debate - but stick around. We've got voter insight, analysis and pop culture tidbits to share.

Here are some of the key developments you may have missed:

• Trump - who was diagnosed with Covid-19 last week - published a new video message promising every American will have access to the same antibody treatment he received
• Trump's doctor has also said the president has had no symptoms for more than 24 hours
• An investigation by USA Today meanwhile found that up to 6,000 people were exposed to the virus at a White House event in September
• And in light of all those virus concerns, tonight's debate will have more precautions, including mandatory masks for the audience, plexiglass dividers and 12ft (3m) of distance between the candidates

• Across the nation, more than four million ballots have already been cast in early voting

Holly Honderich
BBC News, Toronto, Canada

We’ve been asking our readers for their most pressing questions about the US election. Now it’s our turn to respond.

Click here if you want to know more about this project or send in a question of your own.

Richard Brush, 64, from New York asks: Is it true Kamala Harris went to high school in Canada?

It’s true - Kamala Harris does have some semblance of Canadian roots. Harris and her sister, Maya, moved to Montreal when their mother, Shyamala Gopalan, a cancer researcher, took a job at Montreal’s McGill University.

She left Canada after graduating from high school, attending university in the US.

The news that the Canadian-raised (sort of) senator would be Joe Biden’s vice-presidential pick was met with celebration north of the border.

In a tweet, her former high school, Westmount High, said it “couldn’t be more proud” of its graduate.

So how did Harris feel about her time in Canada?

In her memoir, The Truths We Hold, Harris admitted that at the time of her move, the thought of leaving sunny California to a “French-speaking foreign city covered in 12 feet of snow” was “distressing”.

More from that video released earlier this hour by President Trump - who is likely still infected with Covid-19. His main message is that he wants to make Regeneron, the experimental antibody treatment he received during his treatment, free for all Americans affected by Covid-19.

"This was a blessing in disguise. I caught it, I heard about this drug, I said let me take it, it was my suggestion," he says. "I said, let me take it. And it was incredible the way it worked, incredible."

We're expecting the first question in tonight's debate to be about the pandemic - a topic very much on the minds of Americans. The last time a majority of the country approved of the president's handling of the crisis was back in April, data suggests.

These voters in Dayton, Ohio are casting their ballots well ahead of 3 November, thanks to early voting provisions.

Minnesota, South Dakota, Virginia and Wyoming kicked off voting on 18 September, and more than four million Americans have already cast their ballots, according to the United States Election Project. That compares to only 75,000 at this point in 2016.

Ritu Prasad
BBC News writer, Fort Myers, Florida

Image source, Getty Images

Vice-President Pence, who has continued his campaign tour without the president, will make a stop at America's largest retirement community in Florida on Saturday it's been announced.

He'll also host a Latino event in Orlando.

Florida is a key battleground - it's a region where voters are more likely to change parties - but many parts of the Sunshine State are Republican strongholds.

Trump's Mar-a-Lago home is here, and he won Florida with 48% of the vote in 2016. The 2020 Republican National Convention was at one point scheduled here. Florida's two US Senators and its governor are also Trump-loyal Republicans.

Here in Fort Myers, Trump-Pence campaign signs line the main roads and many a yard. There are fewer minorities here, but even among Latinos in more Democratic-leaning areas, Trump has found support.

Cubans have helped shape Florida's Latino vote as the largest Hispanic voter bloc, Pew Research Center reports, external. Most are Republican, and back in 2016, 54% of Cuban Floridians backed Trump, compared to 28% nationwide. This year, just over half say they still approve of Trump.