HELENA, Mont. — Montana Gov. Steve Bullock appointed Lt. Gov. John Walsh Friday to serve out the term of Democratic U.S. Sen. Max Baucus, who will be leaving the seat to become the next ambassador to China.

Walsh, 53, already was a candidate to replace Baucus in this year's elections, and his interim appointment may boost the Democrat in a potential general-election campaign against Republican U.S. Rep Steve Daines.

Republicans are seeking to win a net of six seats in November to gain control of the Senate.

Walsh spent 33 years in the Montana National Guard, and he commanded more than 700 troops in Iraq in 2004 and 2005. He became the state's adjutant general in 2008, resigning from that post in 2012 to run on the bottom half of the Bullock ticket.

"I wanted to appoint someone who I believed would represent the values Montanans hold important," said Bullock, a Democrat, in announcing his decision.

Walsh said he will travel to Washington, D.C., on Monday and will be sworn in the next day. He said he would not be "sucked in" to the political culture of Washington.

"There are too many politicians who put their own political agendas ahead of doing what's right, too many folks who don't take their responsibility seriously," Walsh said.

Walsh spent less than one year as lieutenant governor, his first elected office, before announcing his candidacy for Baucus' Senate seat.

Despite a short political resume, Walsh said his years of public service in the National Guard and his time as lieutenant governor have prepared him for his new role. He also said he will lean on mentors such as Sen. Jon Tester, D-Mont.

The Senate confirmed Baucus on Thursday as the ambassador to China with a 96-0 vote. Baucus has served in the Senate for 35 years, and he announced last year that he would not seek another term.

Walsh will serve the remainder of Baucus' term, which ends in January 2015.

Bullock's choice had been the subject of speculation since Baucus was nominated for the ambassadorship in December. Would the governor appoint Walsh, the candidate he had already endorsed in the election this year, or would he pick a caretaker appointee who had no interest in running for the seat?

The governor said he did not have a short list of finalists and conducted no formal interviews for the position. He said he spoke to people who expressed an interest and only informed Walsh on Thursday night of his decision.

Bullock brushed off questions on whether November's election was a factor in his choice.

"I'll leave it to the voters to decide what happens in November, but I chose the person that I believed would be most effective," Bullock said.

State law leaves the decision of an interim appointment to the governor, without any mention of how to go about doing it. Republican legislative leaders asked Bullock for transparency in the selection process, but Bullock kept a tight lid on his choice, saying only the person "will represent the interests of all Montanans."

One of those GOP leaders, Montana Senate President Jeff Essmann, criticized Bullock for what he called an "arrogant and high-handed" approach to picking Baucus' replacement.

"Instead of doing what would have been easy, setting up an open and transparent process to listen to the people of Montana, Gov. Bullock ducked and weaved so that he could fulfill his duty and complete a backroom deal that was hatched in Washington to benefit Washington, not Montana," Essmann said.

Walsh has come under fire recently amid reports that he was reprimanded in 2010 by the U.S. Army for pressuring Montana National Guard troops to join the National Guard Association of the United States, a private association for which he was seeking a leadership position. In response, Walsh released more than 400 pages of his military records and said what he did was for the good of the Guard.

Besides Walsh, political newcomer Dirk Adams and former Lt. Gov. John Bohlinger also are running for the Democratic nomination.

Walsh raised $583,113 in the final three months of 2013 for his campaign, outpacing Adams' $102,975 — $71,000 of which came from Adams himself, Bohlinger brought in $10,000 in donations, plus another $10,000 of his own money.

Daines is the early front-runner for the Republican nomination and has raised more money than all the other candidates, with more than $1 million in the final three months of 2013.