House members from both parties are facing difficult primary challenges as they try to win reelection amid a voter backlash against Washington.

Incumbents have built-in advantages, including name recognition and more established fundraising networks and campaign operations. But in one of the first primaries of 2018, anti-abortion Rep. Daniel Lipinski Daniel William LipinskiFive things we learned from this year's primaries Hispanic Caucus campaign arm endorses slate of non-Hispanic candidates Bottom line MORE (D-Ill.) was nearly unseated by a first-time candidate running to his left with the help of national progressive groups.

Now, other primary challengers — from those who have never held office to former House members — are hoping to topple incumbents across the country.

Here are the five incumbents most at risk of losing a primary:

Rep. Robert Pittenger Robert Miller PittengerBottom Line North Carolina reporter says there could be 'new crop' of GOP candidates in 9th Congressional District race North Carolina board calls for new election in contested House race MORE (R-N.C.)

Pittenger came exceptionally close to losing a 2016 primary race, defeating Republican primary opponent Mark Harris by just 134 votes.

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Using President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE’s “drain the swamp” slogan in his latest TV ad, Harris has sought to tag Pittenger, who has served in Congress since 2013, as a creature of Washington.

But Pittenger has also tried to tie himself to Trump, who won his district by nearly 12 points in 2016. He accused Harris in an ad of trying to “stop Trump” in the 2016 election.

Support for Trump has become a flashpoint in this race, with both sides accusing their opponent of disloyalty to the president.

But both Republicans initially supported other Republicans in the presidential primary before ultimately backing Trump when it was clear he’d clinch the nomination. Harris backed Sen. Ted Cruz Rafael (Ted) Edward CruzThe Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy Murkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight MORE (R-Texas), while Pittenger supported Sen. Marco Rubio Marco Antonio RubioMurky TikTok deal raises questions about China's role Sunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Florida senators pushing to keep Daylight Savings Time during pandemic MORE (R-Fla.).

So far, recent polls show Pittenger is in much better shape this cycle than he was in 2016. A poll from Civitas Institute found the congressman leading Harris by 32 points.

Rep. Martha Roby Martha Dubina RobyBarry Moore wins Alabama GOP runoff to replace Martha Roby The 14 other key races to watch on Super Tuesday Collins Senate bid sets off game of musical chairs for GOP MORE (R-Ala.)

In a district that voted overwhelmingly for Trump in 2016, Roby had a surprisingly close election against her Democratic competitor after the Republican condemned Trump after the release of the “Access Hollywood” tape.

Now, Roby faces several Republicans in the June 5 primary and her strong rebuke of Trump from 2016 could come back to haunt her.

One of her most notable challengers is Bobby Bright, who held the district from 2009 to 2011 as a Democratic congressman. Roby defeated Bright for the seat in 2010, a wave election when Republicans took back the House amid the rise of the Tea Party.

Bright has defended his switch to the GOP, pointing to other high-profile Republicans in the state who were former Democrats. Bright voted against ObamaCare while serving in the House.

"I tried to be a Democrat, and I didn't do the job as a Democrat that I wanted to do, mainly because my beliefs are conservative and that held me back," Bright said when he announced in early February.

Other Republican opponents are looking to seize on Roby and Bright’s pasts. State Rep. Barry Moore has cast himself as a close ally of the president’s. And he sent an email casting both of them as “Democrats running as Republicans,” specifically pointing to Roby’s past criticism of Trump.

Rich Hobson, the former campaign manager for failed Alabama Senate candidate Roy Moore Roy Stewart MooreVulnerable Senate Democrat urges unity: 'Not about what side of the aisle we're on' Sessions hits back at Trump days ahead of Alabama Senate runoff Judge allows Roy Moore lawsuit over Sacha Baron Cohen prank to proceed MORE, is also running as a Republican.

Rep. Michael Capuano Michael (Mike) Everett CapuanoHillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections 'Markeyverse' of online fans helps take down a Kennedy Inside the progressive hunt for vulnerable House Democrats MORE (D-Mass.)

Capuano has been a progressive staple in the Massachusetts delegation for nearly two decades.

But he’s facing a primary challenge from Boston City Councilor Ayanna Pressley, who says the Boston-area district needs fresh leadership, although she doesn’t differ with him much on policy.

Pressley, who was the first African American elected to Boston City Council, told Politico that she’s raised $100,000 a week since announcing her campaign.

The primary challenge has kept some of Capuano’s colleagues on the sidelines. Reps. Seth Moulton Seth MoultonThe Hill's Morning Report - Presented by Facebook - Markey defeats Kennedy; Trump lauds America's enforcers in Wisconsin Moulton fends off primary challenges in Massachusetts Portland: The Pentagon should step up or pipe down MORE and Niki Tsongas Nicola (Niki) Sauvage TsongasMassachusetts New Members 2019 Dem House candidate says she'll file Clarence Thomas impeachment resolution if elected Lawmakers demand action, hearing in response to VA improperly denying sexual trauma claims MORE and Sens. Elizabeth Warren Elizabeth WarrenJudd Gregg: The Kamala threat — the Californiaization of America GOP set to release controversial Biden report Biden's fiscal program: What is the likely market impact? MORE and Ed Markey Edward (Ed) John MarkeySchumer: 'Nothing is off the table' if GOP moves forward with Ginsburg replacement Democrats see fundraising spike following Ginsburg death Democratic senator calls for eliminating filibuster, expanding Supreme Court if GOP fills vacancy MORE are planning to stay neutral in the race.

Still, Capuano is expected to get some political heavyweights in the state behind him, reportedly including Boston Mayor Marty Walsh (D).

Massachusetts has one of the latest primaries of the cycle, with the vote set for Sept. 4. That gives Pressley time to build up her campaign in what’s expected to be a tough fight.

Rep. Dana Rohrabacher Dana Tyrone RohrabacherDemocrat Harley Rouda advances in California House primary Lawyers to seek asylum for Assange in France: report Rohrabacher tells Yahoo he discussed pardon with Assange for proof Russia didn't hack DNC email MORE (R-Calif.)

Rohrabacher, one of the most vocally pro-Russia members of Congress, has been a prime target for Democrats in 2018 after Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE won his district in 2016.

But Rohrabacher could also be vulnerable to a challenge from a fellow Republican and former ally.

Scott Baugh, a former Orange County GOP chairman and state assemblyman, jumped into the race days before the filing period ended in early March, scrambling the crowded field of candidates taking on Rohrabacher.

Rohrabacher once mentored Baugh, and recruited him to run for the state assembly back in 1995.

Baugh had previously said he wouldn’t run unless Rohrabacher retired. And he angered the congressman in 2016, when Baugh raised about $576,000 for his own bid.