A controversy that has rocked race for the White House likely will be front and center when Hillary Clinton and Donald Trump meet Sunday for their second presidential debate.

Clinton, the Democrat, and Trump, the Republican, come together in St. Louis for a “town hall-style” forum, a format that has produced some memorable moments since it was instituted into the presidential debates in 1992.

The contestants also will be competing for television viewers against a Sunday night NFL game and the Major League Baseball playoffs. But besides the differences in setting and format, changes in the polls and tone of the campaign will play even more major roles.

Trump’s campaign was reeling Saturday after more Republicans called on him to drop from the race and the party to save its money for congressional contests after the publication of a 2005 videotape in which Trump made vulgar and sexually charged comments about women. He talks about grabbing women’s genitalia and attempting to have sex with a married woman. He said women would let him get away with such actions because he was a star.

Clinton too has to deal with a new controversy — though not on the scale of Trump’s.

The WikiLeaks organization posted emails it allegedly hacked from people close to the candidate in which Clinton appears to be more supportive of Wall Street, open trade and open borders than she has claimed on the campaign trial. This could hurt her more with progressive voters (who backed Democrat rival Sen. Bernie Sanders in the primary) than with Republicans or swing voters. But it also could raise more questions about trustworthiness.

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Here are five important factors to keep in mind as the candidates approach the second of three debates:

How Trump handles his newest controversy.

Republicans in conservative states such as Utah, Alabama and West Virginia have said that Trump should quit, that they can’t vote for him or that the GOP should focus on down-ballot races.

Trump said he won’t quit and has hinted that he’ll bring up former President Bill Clinton’s sex scandals and Hillary Clinton’s role.

Running mate Mike Pence said he wouldn’t “condone” or “defend” Trump’s remarks and said Trump has the opportunity “to show what is in his heart when he goes before the nation tomorrow night.”

There’s more pressure on Trump.

Clinton was seen as doing far better than Trump at the Hofstra debate, putting the Republican on the defensive regarding his income taxes, bankruptcies and harsh criticism of a beauty pageant contestant. Trump was aggressive in the first third of the night, saying Clinton didn’t represent a break from the past. But even allies acknowledged the real-estate mogul flailed somewhat through the rest of the debate.

As a result, polls have shown a boost for Clinton.

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Real Clear Politics says an average of national polls shows Clinton with a 4.5 percentage-point lead, up nearly 3 points since the end of September. She also got a bump in some key states.

Trump needs to reverse the trend, analysts said.

“The stakes are much higher for Trump. He has to stop the momentum,” said David Caputo, political scientist at Pace University. With about a month to go in the race, the Republican can’t miss an opportunity to rebound, he said.

“The race is not over, but Clinton created separation,” said Jeremiah Hickey, a St. John’s University professor and expert in political and legal argumentation and debate. He said the fact that Trump’s running mate, Indiana Gov. Mike Pence, had a better showing in the vice presidential debate puts more pressure on the candidate himself.

“He’ll need to exceed the standard of his own running mate,” Hickey said.

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Style and body language will become more important.

The candidates won’t be behind podiums. They’ll have lapel microphones (or hand-held) and will be able to walk around, toward audience members and one another. The audience will be more intimate and closer to the candidates.

The physical changes force candidates to alter their approaches, experts said. You have to be more polite. Arguing over the moderator or over another can come off as rude or insulting. You have to be mindful of personal space.

The format probably isn’t comfortable for either Clinton or Trump, said Jack Brown, a body language expert who has been analyzing the campaign.

“I think that the ‘town hall format’ is not Hillary Clinton’s favorite,” Brown said in an email. “I think she believes she performs better — and in the minds of the electorate — when she debates from behind a lectern. Having said that, of the two candidates, Donald Trump is much more out of his element in the town hall format.”

Trump mainly has campaigned in large venues, on a stage and distant from a crowd and could be awkward in this format, Brown said — but so could Clinton.

“When this advantage gets taken from her, she has to morph into her common-person persona — which many people say is not as likable,” Brown said. “This is her challenge.”

The town hall style has produced some memorable moments and gaffes over the years: Bill Clinton telling an audience member who was struggling economically, “I feel your pain.” President George H.W. Bush looking at his watch, which came off as disinterest even though it wasn’t intended that way. Al Gore coming off as a bully when he walked up very close to George W. Bush.

The questions can be unpredictable. To a degree.

This is the one debate where audience members will participate; they are expected to ask about half the questions on the night.

While this makes for a degree of unpredictability, don’t expect anything out of the blue. The Commission on Presidential Debates prescreens the questions. Critics have said that while this prevents a wild attack on any one candidate, it takes away some authenticity.

The responses should be different, too, than the ones given to a moderator or directed at an opponent.

“You have specific voters asking candidates: How do you solve this problem? How do you speak for this constituency?” Hickey said. “You have to be very clear in a particular proposal. If you take time to make personal attacks, it’s going to look bad for the candidate — not only are you missing an opportunity to connect to real live voters in front of you, but you end up looking small and not presidential.”

The candidates will have prepped more, even if they say they haven’t.

After being criticized for his lack of preparation for the first debate, Trump held a hastily called meeting with supporters in New Hampshire on Thursday. He took questions from audience members and even had a clock on stage at foot level in an attempt to keep answers to about two minutes, according to multiple reports.

But Trump insisted he wasn’t practicing.

“This has nothing to do with Sunday. We’re here because we just wanted to be here. Hillary, frankly, they’re talking about debate prep — that’s not debate prep. She’s resting,” Trump said.

Meanwhile, CNN reported Clinton spent a day at home this week prepping, meeting with a small group of top aides.

“She likes answering questions from individual citizens. She listens hard, she relates to people,” Clinton adviser John Podesta told CNN.