Sen. Debbie Stabenow (D-Mich.), the chairwoman of the Democratic Policy and Communications Committee and a close ally of Senate Majority Leader Charles Schumer (D-N.Y.), announced Thursday she is not running for re-election in 2024. 

The announcement is a blow to Democrats’ hopes of keeping their Senate majority in 2025 as they face a tough Senate map this cycle. 

“Inspired by a new generation of leaders, I have decided to pass the torch in the U.S. Senate. I am announcing today that I will not seek re-election and will leave the U.S. Senate at the end of my term on January 3, 2025,” Stabenow announced Thursday.  

Stabenow, the chairwoman of the Senate Agriculture Committee, says she will focus on passing the farm bill, which provides hundreds of billions of dollars in support to agriculture, in the 118^th Congress. 

“For the next two years, I am intensely focused on continuing this important work to improve the lives of Michiganders. This includes leading the passage of the next five-year Farm Bill which determines our nation’s food and agriculture policies,” she said.  

Democrats have to defend 23 Senate seats in the next election — including those held by independent Sens. Kyrsten Sinema (I-Ariz.), Bernie Sanders (I-Vt.) and Angus King (I-Maine).

Schumer also faces potential retirements in two red-leaning states, Montana and West Virginia, where centrist Sens. Jon Tester (D-Mont.) and Joe Manchin (D-W.Va.) are mulling whether to run for re-election. 

Keeping Sinema’s seat out of Republican hands in 2024 could also be a tough challenge after she announced her decision to leave the Democratic Party and register as an independent. 

Sinema won’t say whether she plans to run for re-election and she is expected to face Democratic and Republican opponents in a three-way general election race if she decides to bid for a second Senate term.

This story was updated at 9:28 a.m.