Gov. Steve Bullock got a boost in his bid for the White House on Sunday with the endorsement of fellow Montana Democrat Sen. Jon Tester, who, like Bullock, has managed to win several statewide elections in a deep-red, predominantly rural state.

Bullock unveiled the endorsement on "Face the Nation" Sunday, saying he's "awfully excited" about the announcement.

"I've known and worked with him for a long time now," he said, referring to Tester. "He's also been such a voice in both rural areas, places that we need to win back, bridging some of the divides."

"Though D.C. hasn't done much — he's been a voice for making sure that we get the big money out of the system, which we have to do," Bullock added.

In a statement to CBS News, Tester, the only working farmer in the Senate, said Bullock could put "politics aside" as commander-in-chief and heal some of the partisan divisions in the country.

"We need someone in the White House who wants to get dark money out of our campaigns and create opportunity in rural America. Someone with a track record of delivering jobs and healthcare, who has proven they can bridge the partisan divide," he added. "That's why I am endorsing my friend, Governor Steve Bullock, to be our next President."

Tester is one of two incumbent Democratic senators who survived tough challenges last year in states President Trump won by more than 10 percentage points in 2016. Bullock, meanwhile, secured a second term by a 4-point margin in 2016, when Mr. Trump won Republican-leaning Montana by nearly 21 percentage points.

Asked about his low standing in polls of the crowded field of Democrats running for president, the Montana governor pointed to his relatively recent entry into the race and stressed that he believes he's the only candidate who can woo voters in rural areas of the country where the president is deeply popular.

"I've led with a legislature that's about 60% Republican, but we've been able to get progressive things done like getting dark money out of our elections and getting health care for 10% of my population, record investments in education," he said. "So, look, the number one focus certainly is beating Donald Trump. But we also got to bridge some of the divides to make our economy and government work for folks outside of D.C. again."

Last week, Bullock's campaign and a group of Montana Democrats denounced a debate rule by the Democratic National Committee (DNC) which they believe hinders the Montana governor's chances of qualifying for debates. The new rule disqualifies a Washington Post/ABC poll — a move Bullock's campaign said will only affect him.

Bullock said the DNC should prioritize the preferences of the electorate.

"I hope that the DNC will play fair by everyone in the field because that's their role is to facilitate the voter's options. Not to try to limit it," he added.

Tim Perry contributed to this report.