Washington CNN  — 

Montana Gov. Steve Bullock formally announced Monday that he will run for the US Senate, improving Democrats’ chances of winning a majority in the chamber this fall.

“As governor, I’ve worked my level best to represent all Montanans and leave this place we call home better than I found it, and in a time when our politics is more divided than ever, we’ve been able to accomplish a great deal for the people of our state,” Bullock said in a statement. “We can’t say the same about Washington, where they can’t tackle the difficult challenges like health care costs, climate change and a changing economy or even the ones we agree on like strengthening our infrastructure, lowering drug prices and banning dark money from our federal elections.”

He continued, “After hearing from Montanans and talking to Lisa and our kids, we decided now is no time to be on the sidelines, and that’s why I’m running so we can make Washington work more like Montana.”

CNN reported last week that Bullock was planning to run. In recent weeks, Bullock’s initial resistance to a Senate campaign has eased, officials said, with his family now warming to the idea. In conversations with party leaders, he has also cited the gravity of the times and the importance of Democrats trying to win back the chamber. Bullock would face Republican Sen. Steve Daines, who has built up an impressive $5 million war chest, in a state President Donald Trump carried by double digits in 2016.

Nathan Brand, a spokesman for the National Republican Senatorial Committee, linked Bullock to establishment Democrats shortly after the governor announced his run.

“One can see why, given their visceral disdain for the Montana way of life, Washington Democrats rolled out the red carpet for Bullock. Meanwhile, Steve Daines always puts Montana first, is a proven leader and a strong ally for President Trump,” Brand said.

Bullock, a former 2020 Democratic presidential contender, previously said he had no interest in serving in the US Senate and would not be on the Montana ballot this fall.

Democrats need to win the White House and a net gain of three seats in the Senate to flip the chamber, or four seats if they don’t defeat Trump. Bullock, who’s won two terms as governor, made his ability to win statewide in a red state the cornerstone of his presidential campaign.

This story has been updated to include additional reaction.

CNN’s Jeff Zeleny and Alex Rogers contributed to this report.