Trump planned to rally supporters on Thursday in Great Falls in a bid to boost the candidacy of state Auditor Matt Rosendale, the Republican challenger to Tester.

Trump has made the Montana Senate race a priority for the November elections. He blames Tester for derailing the nomination of White House physician Ronny Jackson as Veterans Affairs secretary. Tester is the top Democrat on the Senate Veterans Affairs Committee. He went public with multiple allegations of misconduct against Jackson.

Jackson denied the allegations but ultimately withdrew his nomination.

Tester has said he would not have handled the situation differently.

He has given Trump a tongue-in-cheek welcome to Montana by taking out a full-page ad in 14 newspapers thanking the president for signing 16 bills that the Democrat sponsored or co-sponsored.

It says, "Welcome to Montana, and thank you President Trump for supporting Jon's legislation to help veterans and first responders, hold the VA accountable, and get rid of waste, fraud and abuse in the federal government."

The Tester campaign also plans to run a radio ad across the state touting his bills that Trump has signed.

Australian Associated Press