I WON’T BACK DOWN: Mike Lee provokes leadership showdown.

Lee’s gambit also could disrupt the unity within the party fostered by its stance against the president’s Supreme Court nomination — and further the senator’s reputation as a conservative bomb-thrower.

But Lee is pressing his case, insisting that the position of Republican Policy Committee chairman is wide open for 2017.

“I have no interest running against John Barrasso for this or anything else. I am interested in running for the open-seat Republican Policy chair,” Lee said in an interview on Wednesday.

That Lee believes the seat is still open is a direct challenge to McConnell, who brought Republican Secretary Laura Dove into the Tuesday caucus lunch to explain that Barrasso is eligible for another two-year term. But if Lee wins the argument, he’d imperil three-fifths of the leadership team: Barrasso, Republican Conference Chairman John Thune of South Dakota and Conference Vice Chairman Roy Blunt of Missouri all took their jobs in late 2011.

Surely a little fresh blood near the top of the GOP Senate leadership couldn’t hurt.