Republican voters in Arizona and Florida are expected to pick Sens. John McCain and Marco Rubio as their respective U.S. Senate nominees when they go to the polls on Tuesday, but one name not on either ballot, Donald Trump, looms large.

The Republican presidential nominee has endorsed both McCain and Rubio in their re-election bids even though he has rocky relations with both senators.

Trump offended McCain and many other Republicans last year by suggesting that the maverick senator and party's 2008 presidential nominee was anything but a war hero because he was captured during the Vietnam War after his airplane was shot down during a bombing mission.