BILLINGS, Mont. (AP) — Donald Trump Jr. is set to rally Montana Republicans after his father said Democratic U.S. Sen. Jon Tester must pay "a big price" for releasing allegations that derailed the White House's Veterans Affairs nominee.

The president's son is the keynote speaker at the state GOP's platform convention Friday in Billings.

He is expected to promote Republican senate candidate and state Auditor Matt Rosendale, who won a four-way primary contest this month and faces Tester in the November election.

Tester, who is seeking a third term, drew President Donald Trump's ire in April by releasing allegations that VA nominee Ronny Jackson overprescribed drugs and got drunk on duty.

Tester says he hopes the president himself visits the state to see its infrastructure needs and the security challenges on the U.S.-Canada border.