Montana Democratic Party officials say they'll hold a special nominating convention Aug. 16 in Helena to select a replacement candidate for Sen. John Walsh in the U.S. Senate race.

The convention will start at 9 a.m. at the Lewis and Clark County Fairgrounds. It will include leaders from county party committees, federal and statewide elected officials and the party's executive board. Party spokesman Bryan Watt says the intent is to have a candidate nominated by the end of the day.

A new candidate must be selected before Aug. 20. He or she will run against Republican Rep. Steve Daines and Libertarian Roger Roots.

Walsh bowed out Thursday amid allegations he plagiarized portions of a 2007 research paper he submitted to earn a master's degree from the U.S. Army War College.