They'll discuss the usual issues, but look for Mike Pence and Tim Kaine to have a lot to say about their running mates on Tuesday night.
They'll square off in the one and only vice-presidential debate.
It will be held in Farmville, Virginia. Pence told supporters at a rally in Virginia that he hopes they get to talk about their own records.
Pence is governor of Indiana and served in Congress for a decade.
Kaine is a U.S. senator and former governor of Virginia.