Republican U.S. presidential candidate Donald Trump and Democratic Vice President Kamala Harris will meet on Tuesday to debate a phenomenon that may prove pivotal in their pitched battle for the White House.

The ABC News-hosted debate at 9:00 p.m. ET (0100 GMT on Wednesday) takes place just eight weeks before the November 5 election, with both candidates locked in a tight race that could still easily swing in either direction. Early voting will start in some states just days after the debate.

The encounter is particularly important for Ms Harris, with opinion polls showing that more than a quarter of likely voters feel they do not yet know enough about her, in contrast to the well-known Mr Trump.

The nationally televised debate also offers Ms Harris, a former prosecutor, a chance to make her case against Mr Trump, whose felony convictions, outspoken backing for supporters convicted of the January 6, 2021, attack on the U.S. Capitol, and frequent falsehoods all offer plenty of fertile ground.

It will be the first time the two candidates have met and follow weeks of personal attacks on Ms Harris by Mr Trump and his allies that have included racist and sexist insults.

A similar outburst on stage could turn off undecided voters, according to John Geer, a professor at Vanderbilt University and an expert on presidential politics.

Mr Trump’s advisers and fellow Republicans have urged him to focus on Tuesday on illegal immigration and high prices, issues that play well with voters, and portraying Ms Harris as too liberal for the country.

“There’s no floor for him in terms of how low he will go, and we should be prepared for that,” Ms Harris said in a radio interview that aired on Monday.

Presidential debates do not always move the needle, but they can transform the dynamics of a race. President Joe Biden’s faltering performance against Mr Trump in June was so damaging that it eventually led him to abandon his campaign.

In a contest that could again come down to thousands of votes in a handful of states, even a small shift in public opinion could alter the outcome.

The two candidates are effectively tied in the seven battleground states likely to decide the election, according to polling averages compiled by the New York Times.

“There is more for Kamala Harris to gain and more for her to lose,” said Mitchell McKinney, a former adviser to the U.S. Commission on Presidential Debates, since she remains somewhat of an unknown for many voters.

Viewers will be looking for where she stands on various issues. But just as important, they will be looking to see how she handles herself against Mr Trump.

Mr Trump, by contrast, is already well-defined. “You’re either for him or against him” at this point, Ms McKinney said.

The 90-minute debate will take place at the National Constitution Centre in Philadelphia. As agreed by the campaigns, there will be no live audience, and microphones will be muted when it is not a candidate’s turn to speak.

(Reuters/NAN)