Rep. Darrell Issa Darrell Edward IssaTrump-free Kennedy Center Honors avoids politics Giffords gun group targets Issa over concealed carry bill The Hill Interview: Missouri Republican has gavel on his radar MORE (R-Calif.) announced Wednesday that he will not seek reelection this year, increasing Democrats’ chances of flipping his swing district in their favor.

Issa barely won reelection in 2016 by just over half a percentage point in a San Diego-area district that went for Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonGrassley blasts Democrats over unwillingness to probe Clinton GOP lawmakers cite new allegations of political bias in FBI Top intel Dem: Trump Jr. refused to answer questions about Trump Tower discussions with father MORE by about 7 points.

“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.

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The former House Oversight Committee chairman faced a tough path to reelection in an increasingly Democratic district. The lack of a 17-year incumbent will now make it easier for Democrats to win the district as they seek to win back the House this year.

Issa’s retirement offers yet another boon to House Democrats in California over the last three days.

House Foreign Affairs Committee Chairman Ed Royce Edward (Ed) Randall RoyceState Dept insists cyber a priority despite office closure It’s time to use surgical strikes, naval blockades and more on North Korea Giffords targets 8 Republicans on conceal and carry in new ads MORE (R-Calif.), who also represents a district won by Clinton, announced on Monday that he won’t seek reelection this year either.

Royce won reelection by 14 points even though Clinton carried his district by nearly 9 points, compared to Issa’s razor-thin margin.

“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,” said Democratic Congressional Campaign Committee spokesman Drew Godinich.

Democrats need to flip 24 seats to win back the House majority.

Issa’s retirement is another data point in the signs of a possible Democratic wave in this year’s midterm elections.

His departure means that House Republicans will have to defend at least 31 open seats this year due to retirements, resignations and lawmakers seeking other office. By contrast, House Democrats will only have 15 open seats so far.

Eight House GOP committee chairmen have decided to call it quits this election cycle, including three in the last week: Royce, House Transportation Committee Chairman Bill Shuster William (Bill) Franklin ShusterThe Hill Interview: Missouri Republican has gavel on his radar For Trump, GOP tax bill could have big downside GOP chairman fundraising for conservative House member MORE (R-Pa.) and House Administration Committee Chairman Gregg Harper Gregory (Gregg) Livingston HarperMcCarthy: ‘Zero tolerance’ for sexual harassment Taxpayers funded GOP lawmaker’s K sex harassment settlement: report Ethics panel asks for details of past harassment cases against serving lawmakers MORE (R-Miss.).

Royce and Shuster, along with Judiciary Committee Chairman Bob Goodlatte Robert (Bob) William GoodlatteRosenstein to testify before House Judiciary Committee next week Conservative pressure on Sessions grows Clock ticking down on NSA surveillance powers MORE (R-Va.), Financial Services Committee Chairman Jeb Hensarling Thomas (Jeb) Jeb HensarlingRyan pledges 'entitlement reform' in 2018 Consumers need a hero, not a hack, to head the CFPB Right scrambles GOP budget strategy MORE (R-Texas) and Science Committee Chairman Lamar Smith Lamar Seeligson SmithOvernight Cybersecurity: Panel pushes agencies on dropping Kaspersky software | NC county won't pay ransom to hackers | Lawmakers sound alarm over ISIS 'cyber caliphate' The Hill Interview: GOP chairman says ‘red flags’ surround Russian cyber firm Seven Texas lawmakers leaving Congress means a younger, more diverse delegation MORE (R-Texas), were all bound by GOP rules limiting chairmen to three consecutive two-year terms.

Issa’s four years as Oversight Committee chairman were at times rocky.

He frequently clashed with Democrats on the committee as he pursued holding then-Attorney General Eric Holder Eric H. HolderFBI director defends agency after Trump attacks: It's an 'honor to represent you' FBI agents fire back at Trump: Saying we're not dedicated is 'simply false' Holder hits back at Trump: The FBI’s reputation is not in 'tatters' MORE and former IRS official Lois Lerner in contempt of Congress over a gun-tracking program and alleged scrutiny of conservative groups, respectively.

Issa was also one of the wealthiest members of Congress due to his prior career leading an automobile security device business.

Without Issa on the ballot, the primary to nominate candidates for the district this year could be messy.

Under California’s primary system, the top two vote-getters advance to the general election, regardless of party. That means the general election could feature a race between two Democrats if a Republican fails to get as many votes.

At least four Democrats are running for the seat. They include retired Marine colonel Doug Applegate, who challenged Issa in 2016; Sara Jacobs, a former State Department and United Nations aide who has been endorsed by EMILY’s List; Navy veteran Paul Kerr; and environmental attorney Mike Levin.

But National Republican Congressional Committee Chairman Steve Stivers Steven (Steve) Ernst StiversThe Hill Interview: Missouri Republican has gavel on his radar GOP House campaign group chief touts Republican success in Georgia race White House bashes GOP effort to delay regs on predatory loans to troops MORE (R-Ohio) predicted that the primary would be nastiest on the Democratic side.

"In the 49th district, Democrats are locked in what is fast becoming one of the bloodiest primaries in America. While Democrats fight with each other, Republicans will focus on fighting Democrats – and that's how we plan to win. We look forward to facing whoever limps out of the Democrats' battle royale: black and blue, and broke,” Stivers said.

--This report was updated at 11:42 a.m.