“I am ending my campaign so that I can focus on fulfilling the responsibility entrusted to me as your U.S. senator,” Walsh said in a statement to supporters. “You deserve someone who will always fight for Montana, and I will.”

The Montana Democratic Party now will choose a replacement for Walsh to appear on the Nov. 4 ballot, along with Republican Rep. Steve Daines and Libertarian Roger Roots.

The party has to select a new Senate candidate at a nominating convention by Aug. 20. About 175 delegates, including statewide and federal elected officials, county party committee leaders and the party executive board members, will pick the nominee.