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WASHINGTON, DC - FEBRUARY 09: Sen. Jon Tester (D-MT) speaks to reporters in the Senate Subway on his way to a closed-door briefing for Senators about the Chinese spy balloon at the U.S. Capitol on Thursday, Feb. 9, 2023 in Washington, DC. (Kent Nishimura / Los Angeles Times via Getty Images)
Washington CNN  — 

Montana Sen. Jon Tester announced Wednesday morning that he will seek reelection in 2024, providing a boost to Democrats’ hopes of retaining the Senate.

“It’s official. I’m running for reelection,” Tester tweeted. “Montanans need a fighter that will hold our government accountable and demand Washington stand up for veterans and lower costs for families. I will always fight to defend our Montana values. Let’s get to work.”

Tester is one of several Democratic senators in red and purple states who are likely to face competitive challenges this cycle. Along with West Virginia Sen. Joe Manchin, Tester was one of the top incumbents being urged by party leadership to seek reelection.

Reacting to the announcement, the National Republican Senatorial Committee swiftly moved to tie Tester to President Joe Biden in the deep-red state, calling him the president’s “favorite senator.”

Democrats have a difficult road to maintain their slim 51-49 majority, with 23 seats to defend compared to just 11 for the GOP.

Plus, they’ll have to hold onto Democratic seats in GOP terrain, such as in Ohio and West Virginia – not to mention keep their seats in swing states like Pennsylvania, Wisconsin, Michigan and Nevada. The map provides them with scant pickup opportunities, since Republican incumbents are mostly running in ruby-red states or states that have trended to the GOP, like Florida.

Tester has nearly $3 million in his Senate campaign account as he gears up for the campaign.

This story has been updated with additional background information.

CNN’s Melanie Zanona contributed to this report.