Kamala Harris faces voters' questions at a live forum Wednesday in must-win Pennsylvania as the vice president and her rival Donald Trump battle for undecided voters in the closing stretch of an extremely close White House race.

The pace of campaigning has been intensifying in the electoral fight that is nearing its November 5 apogee after twists, turns and a fair bit of drama.

Harris will be near Philadelphia for a CNN town hall-type meeting with voters, but there is not one planned for Trump despite the news channel's offer to hold a separate forum for him.

Pennsylvania is a coveted prize for the candidates in the election in which more than 240 million Americans are expected to vote, and Harris and Trump have made repeated appearances there and across swing states.

The 78-year-old Republican will hold his own town hall event in the southern battleground state of Georgia, which Trump narrowly lost to Biden in 2020 but won in 2016.

Trump used a Tuesday rally in North Carolina to attack Harris, repeatedly calling her stupid and arguing she doesn't have the "smarts or the strength" to lead the United States.

About 18 million Americans have already voted by mail or in person -- representing more than 10 percent of the total in 2020.

Harris, 60, said Tuesday that America is "absolutely" ready to elect its first woman president.

"People are exhausted with Donald Trump and his approach, because it's all about himself," she said.

Can polls be trusted?

Harris's arrival in the campaign shook up the country, which was expecting a rematch between President Joe Biden and his predecessor Trump.

Since Biden's shock withdrawal after a disastrous debate performance, the race between Trump and Harris has been one of the tightest in American history.

It's hard to know the degree to which opinion polls are accurate, as they have in the past underestimated support for Trump but also failed to predict the level of support for Democrats.

While the ex-president hammers on his promises of a migrant crackdown and economic good times after a period of high inflation, his rivals raise concerns about his willingness to honor American democracy.

The Harris campaign has also begun to hammer at his mental and physical fitness to occupy the Oval Office while trying to woo moderate Republican voters.

One of Trump's top aides as president, former Marine general John Kelly, confirmed Tuesday to The New York Times previous reports that he considered the Republican to be a fascist.

"Certainly the former president is in the far-right area, he's certainly an authoritarian, admires people who are dictators -- he has said that. So he certainly falls into the general definition of fascist, for sure."

Biden, who has been an infrequent presence in Harris's campaign, took a shot at Trump on Tuesday by re-wording the ex-president's notorious anti-Hillary Clinton chant of "Lock her up".

On a visit to New Hampshire, Biden told a small crowd that "we got to lock" Trump up –- adding quickly, "politically lock him up."

With Trump facing multiple pending criminal charges as he competes against Harris to succeed Biden, the White House has been very careful not to weigh in on the Republican's legal problems.

© Agence France-Presse