California Republican Rep. Darrell Issa will retire at the end of his term, he announced Wednesday.
Issa, one of the wealthiest members of Congress and among the best-known due to his reputation as a conservative attack dog, is bowing out of what would have been one of the nation's most hotly contested congressional races.
"Throughout my service, I worked hard and never lost sight of the people our government is supposed to serve. Yet with the support of my family, I have decided that I will not seek re-election in California's 49th District," Issa said in a statement Wednesday.
He nearly lost his seat in 2016, besting Democrat Douglas Applegate -- among the four Democrats running this year -- by less than a percentage point. It's among seven Republican-held districts in California that Hillary Clinton won that year -- carrying Issa's by 8 percentage points.
His decision not to run for re-election comes the same week that Rep. Ed Royce, the powerful chairman of the House Foreign Affairs Committee and another California Republican whose district includes parts of Orange County, announced his retirement.
Royce and Issa's districts are both in expensive television markets -- further stretching national Republicans who are on defense across dozens of districts in the 2018 midterm elections.
Diane Harkey, a former state lawmaker who is now an elected Republican representative on the California State Board of Equalization, a tax administration board, is poised to enter the race, a Republican source said.
Applegate, a retired Marine colonel, and three other Democrats are running: Businessman Paul Kerr, environmental attorney Mike Levin and Sara Jacobs, who worked in foreign policy at the State Department and United Nations.
"California Republicans clearly see the writing on the wall and realize that their party and its priorities are toxic to their re-election chances in 2018," Democratic Congressional Campaign Committee spokesman Drew Godinich said.
In a statement, Rep. Steve Stivers, the National Republican Congressional Committee chairman, said the GOP hopes an expensive and divisive Democratic contest in California's primary will allow the party to hold the seat.
"While Democrats fight with each other, Republicans will focus on fighting Democrats -- and that's how we plan to win," Stivers said.