(NewsNation) — The second and final presidential debate is currently scheduled for Sept. 10 but with President Joe Biden out of the race, a lot could change over the next month.

Biden has endorsed Vice President Kamala Harris, who is now the frontrunner for the Democratic nomination. Harris told reporters on Thursday that she’s “ready to debate Donald Trump” and accused the former president of “backpedaling” away from the ABC News event he had previously agreed to.

Trump has hedged in recent days, suggesting the next debate be held on Fox News rather than ABC, which he called “very biased” in a Truth Social post. A day later he said he hopes “there will be many” debates.

On Thursday, the Trump campaign said it would not agree to a debate with Harris until “Democrats formally decide on their nominee.”

Harris could have the nomination wrapped up by Aug. 7 after Democrats decided to move forward with a plan to vote virtually before the convention. An Associated Press survey suggests Harris does have the necessary support to become the party’s nominee.

NewsNation senior political contributor George Will thinks Harris will have to improve from her debate performance in the 2020 Democratic primary in which she blasted Biden’s civil rights record: “If that’s her idea of a winning debate strategy, the roof is going to fall in.”

Will a Trump-Harris debate happen?

On a Tuesday call with reporters, Trump said he’d like to debate Harris “more than once” but did not commit to appearing at the debate that’s already on the books, according to the Associated Press.

Jason Miller, a senior adviser to the Trump campaign, told Axios a debate “will happen” but that the campaign is “non-committal” to the Sept. 10 debate.

NewsNation political and economic contributor Mick Mulvaney said he expects at least one debate between Harris and Trump but doesn’t think either campaign knows exactly what they want right now. It could depend on what the polls say in the weeks ahead.

“Generally speaking, people who are behind want more debates than people who are ahead,” Mulvaney said.

He added: “If Joe Biden had stayed in this race, I think there would be zero chance that Donald Trump would have agreed to that second debate.”

Currently, Trump holds a two-point lead over Harris, according to The Hill/Decision Desk HQ election center.

What are the stakes of a presidential debate?

If the first debate was any indicator, a terrible performance can sink a campaign. Calls for Biden to drop out only grew loud after his dismal showing. Even so, Mulvaney thinks Biden’s post-debate collapse was an exception, not the new norm.

“In a world of social media and constant information about all the candidates, I’m not sure if debates add as much as they used to,” he said.

The timing of future debates could end up being more important than how they play out. Last month’s face-off was historically early in the election cycle, a stage of the race when voters aren’t as tuned in.

The debate scheduled for Sept. 10 is also earlier than normal. In 2020, Biden and Trump debated on Sept. 29 and Oct. 22. Four years before that Trump and Hillary Clinton debated three times between Sept. 26 and Oct. 19.

Research suggests the impact of debates decays rather quickly and any bumps or declines in the polls tend to wash out before the election. An analysis by Pew Research suggests voters do find debates useful but don’t swing most people one way or another.

What goes into a presidential debate?

From 1988 to 2020, presidential debates were organized by the Commission on Presidential Debates (CPD), a nonprofit, bipartisan group. CPD was responsible for selecting the time, place, moderators and even the debate format, which evolved over the years.

Typically there have been three presidential debates and one vice presidential debate, usually held on university campuses. The commission set the rules, and then the event is broadcast across all major networks. Moderators selected the questions and neither the CPD nor the candidates knew them beforehand.

In 2022, the Republican National Committee (RNC) withdrew from the commission, citing bias against GOP candidates. Then-RNC Chairwoman Ronna McDaniel said the commission refused to enact “commonsense reforms” like “hosting debates before voting begins and selecting moderators who have never worked for candidates on the debate stage.”

Biden’s campaign also voiced concerns about the CPD’s scheduling this election cycle.

This year, the two campaigns bypassed the commission and scheduled two debates on their own, one in June on CNN and another in September on ABC.

Rather than allowing an outside group to set the rules, the Trump and Biden campaigns negotiated a unique set of terms for the first debate, which included no live studio audience, no notes and no help from aides.

It remains to be seen whether the next scheduled debate will go forward as planned, or if more debates will be added. Earlier this week Fox News invited Trump and Harris to debate on Sept. 17.

The Associated Press contributed to this report.