6 Questions Ahead Of The 1st Trump-Biden Presidential Debate

President Trump and Democrat Joe Biden square off in the first of three general-election presidential debates Tuesday night.

The debate is high stakes and carries risks for both candidates.

Here are six questions ahead of the debate, to be moderated by Fox News Sunday host Chris Wallace beginning at 9 p.m. ET and held at Case Western Reserve University in Cleveland.

1. Can Trump avoid the sitting-president first-debate slump?

Presidents up for reelection often struggle in their first debates. It happened to Barack Obama, both Bushes, Ronald Reagan and Jimmy Carter. Some recovered; some didn't.

"What happens with an incumbent president is they spend four years in office being deferred to and agreed with," said Alan Schroeder, author of Presidential Debates: Fifty Years of High-Risk TV. "It's difficult for staff to challenge a sitting president directly, so by the time they get up on the debate stage, they're not used to being spoken to forcefully and directly and being criticized. They're also by definition out of practice."

Trump, of course, defies the odds, breaks the rules and seems constantly embattled, so maybe it won't matter. An NBC report this month indicated that Trump didn't appear to be taking debate prep seriously or holding mock sessions at all. But another from the Washington Post on Friday shows Trump is preparing blistering, personal attacks against Biden.

How Trump holds up in a serious, 90-minute debate after being president for almost four years with a record to defend — and not being the outsider throwing rocks — is a real wild card.