What to watch for in Thursday’s Biden-Trump presidential debate

FILE — President Donald Trump, left, and Democratic presidential nominee Joe Biden participate in the second presidential debate at Belmont University in Nashville, Tenn., on Oct. 22, 2020. Biden is willing to debate Trump at least twice before the election, and as early as June — but his campaign is rejecting the nonpartisan organization that has managed presidential debates since 1988, according to a letter obtained by The New York Times. (Erin Schaff/The New York Times)

Viewers look on at the first presidential debate between President Donald Trump and Joe Biden during a watch party in 2020 in Las Vegas. (Bridget Bennett/The New York Times)

Combination picture showing U.S. President Joe Biden delivering remarks in March in Las Vegas, Nev. and Republican presidential candidate and former U.S. President Donald Trump taking the stage in January in Atkinson, N.H. (REUTERS/Kevin Lamarque and Elizabeth Frantz/File Photo)

The two oldest candidates ever to run for U.S. president meet on Thursday for a televised debate unlike any other. One accuses his rival of being unhinged and a danger to democracy, while the other accuses his opponent of being senile and corrupt.