Daines raised approximately $415,000 in the last three months, according to a source close to the campaign who said it "demonstrates Daines's growing consideration of this race."

That's a jump from the $250,000 he raised in the first three months of the year.

The first-term congressman is seriously mulling a run for the seat held by retiring Sen. Max BaucusMax Sieben BaucusSteady American leadership is key to success with China and Korea Orrin Hatch, ‘a tough old bird,’ got a lot done in the Senate Canada crossing fine line between fair and unfair trade MORE (D-Mont.), and is the GOP's most likely top-tier candidate. Democrats are hoping that former Montana Gov. Brian Schweitzer (D) will jump in on their side. Recent polls show a tight race if the two face off.