WASHINGTON – Democratic Sen. Jeff Bingaman of New Mexico announced Friday he will not seek another term in 2012.

"It's obviously not easy to make the decision to leave the Senate," Bingaman said at a press conference. "There's obviously important work to be done... But that will undoubtedly be true at the end of every future Congress, as well. I think the simple truth is there is no ideal time to leave the Senate."

The news was first reported by the Washington Post's Chris Cillizza.

Bingaman, 67, is the chairman of the Senate Committee on Energy and Natural Resources, and has served five six-year terms in the Senate.

"After 30 years, I think I've given this my best effort, and I think this is a good time for me to make the decision," he said.

Bingaman joins three Senate Democrats -- Jim Webb (VA), Joe Lieberman (CT) and Kent Conrad (ND) -- in calling it quits before a consequential election where the Democratic majority in the chamber could be in danger.

Two Republicans have also announced their retirements ahead of 2012 -- Sens. Jon Kyl (AZ) and Kay Bailey Hutchison (TX).

Twenty-three Democratic seats are up for grabs in 2012, as compared to ten Republican seats.

Cillizza reports that the likely Democratic contenders to replace Bingaman are Lt. Gov. Diane Denish and Reps. Martin Heinrich and Ben Ray Lujan. He adds that former Rep. Heather Wilson and Rep. Steve Pearce may seek the Republican nomination for the seat.