John McCain won the Republican nomination to seek a sixth Senate term in Arizona, defeating conservative primary challenger Kelli Ward Tuesday night.

Ward ran much of Donald Trump's platform against McCain. She opposed the Iraq war and has been a firm critic of McCain's immigration and foreign policies. She has raised his age as an issue — at 80, McCain is already two years older than his Senate predecessor Barry Goldwater at retirement — and described him as too weak to win in November. Many who cheered Paul Nehlen's unsuccessful race against House Speaker Paul Ryan are now boosting Ward.

The incumbent's supporters have fired back with ads Ward has decried as part of a "sexist smear" campaign. One features her singing the Patsy Cline hit "Crazy" and suggests it is an apt description of the Republican Senate hopeful. "These tactics are exactly what we've come to expect from the ultimate establishment insider when he's not busy calling for 'civility' while labeling conservatives as crazies, hobbits, and wacko birds," Ward said in a statement.

McCain was in a tough spot. He needed every Republican vote he can get against Ward, so he has reluctantly endorsed the GOP presidential nominee who questioned whether the senator's capture in Vietnam made him less of a war hero. Trump has equally reluctantly endorsed him.

McCain now faces an even bigger challenge against Democrat Ann Kirkpatrick this fall with the top of the Republican ticket potentially dragging him down. Both the Senate and presidential races in usually Republican Arizona are uncharacteristically close. It's been speculated that McCain might run away from Trump once safely re-nominated, but the senator has denied it.