“The problem is, Washington is broken, it’s increasingly mired in political gridlock, and there’s virtually zero cooperation between the two parties. That’s not the kind of government I grew up with, and it’s precisely why I know I can do more for the Los Angeles region on the Board of Supervisors,” Hahn said in a statement announcing her decision.

Her district, California’s 44th, is almost certain to stay in Democratic hands; President Barack Obama won 85 percent of the vote there in 2012.

Hahn, who was first elected to the House in 2011, said she intends to finish her term and pursue bipartisan policies in Congress before leaving. She also quickly endorsed state Sen. Isadore Hall, a longtime friend and ally, to succeed her. Hall jumped into the race just hours after Hahn’s announcement.

“I know he’ll be a strong leader for the residents of the 44th District as their next Representative in Washington,” Hahn said in a statement.

Hall has been lining up a slew of important endorsements, consultant Dave Jacobson, who represents both Hahn and Hall, told POLITICO earlier this month. Hall has secured the backing of Reps. Ted Lieu, Norma Torres, Karen Bass and Juan Vargas, as well as former Rep. Diane Watson and Compton Mayor Aja Brown, Jacobson said.