Rep. Charlie Dent (R-Pa.) speaks on Capitol Hill in Washington on March 23. Dent, leader of an influential caucus of GOP moderates in the House, announced he will not seek an eighth House term next year. (J. Scott Applewhite/AP)

Rep. Charlie Dent of Pennsylvania, an outspoken leader of the Republican Party’s dwindling moderate wing, said Thursday he will not seek reelection.

The retirement of the seven-term member will force Republicans to defend a third open seat in a swing district in a difficult midterm election cycle. Rep. Ileana Ros-Lehtinen (R-Fla.) announced in April that she would not run again, and Rep. Dave Reichert (R-Wash.) followed suit Wednesday, heralding a potential rash of retirements that GOP leaders fear could imperil their House majority.

Dent is a co-chairman of the Tuesday Group, a caucus of several dozen House Republican moderates that has positioned itself as the “governing wing” of the GOP, more interested in common-sense legislating than conservative orthodoxy.

“Accomplishing the most basic fundamental tasks of governance is becoming far too difficult,” Dent said in an interview Thursday evening. “It shouldn’t be, but that’s reality.”

Dent said he decided in midsummer not to seek reelection in Pennsylvania’s 15th Congressional District after serving in the state legislature and in Congress for a combined 27 years. But he kept his decision close to the vest until Thursday when he told, among others, House Speaker Paul D. Ryan (R-Wis.) and Rep. Steve Stivers (R-Ohio), chairman of the National Republican Congressional Committee.

“It’s just safe to say that they would both prefer I’d run for reelection,” Dent said of those conversations. “But they understand.”

His district, encompassing the cities of Allentown and Bethlehem and much of Pennsylvania’s Lehigh Valley, leans Republican, though not overwhelmingly so. It leans GOP by four points, according to the nonpartisan Cook Political Report, though Dent has shown significant crossover appeal. Donald Trump carried the district last year by eight points, while Dent won by 20 points.

Dent is chairman of the appropriations subcommittee on military construction and veterans affairs, a powerful post that directs tens of billions of dollars in spending yearly. But he is best known on Capitol Hill as a critic of his party’s far right — especially its unwillingness to compromise with Democrats on such basic tasks as passing routine spending bills and increasing the federal debt limit. But he has also bucked the party on more substantive policy matters, including the House GOP bill earlier this year to repeal parts of the Affordable Care Act.

Dent said his decision not to seek reelection has less to do with President Trump or the current Congress than with his own personal ambitions. He said he considered retiring after each of the previous two Congresses but opted against it after winning top committee posts. “I guess never anticipated I’d get to this level of seniority this quickly, honestly, so I think that’s partly what caused to stay a little longer,” Dent said.

In a statement announcing his decision, Dent expanded on his record: “I have done my best to make a meaningful, positive impact. As a member of the governing wing of the Republican Party, I’ve worked to instill stability, certainty and predictability in Washington. I’ve fought to fulfill the basic functions of Government, like keeping the lights on and preventing default. Regrettably, that has not been easy given the disruptive outside influences that profit from increased polarization and ideological rigidity that leads to dysfunction, disorder and chaos.”

Dent suggested in his statement that he would not leave the political sphere entirely: “I promise to continue my role, both inside and soon outside of government, of giving voice to the sensible center and working to solve problems for the American people through smart policy — the product of negotiation, cooperation and inevitably, compromise.”

Stivers said in a statement late Thursday that Dent’s seat would remain in Republican hands. “Voters sent a clear message by delivering the district for President Trump last November — and we are confident that PA-15 will remain solidly under Republican control,” he said.

Democrats, meanwhile, called Dent’s retirement a clear opportunity, one that “opens up a competitive seat that President Obama won in 2008 and narrowly lost in 2012, and Democrats are confident that a strong candidate will step up to run and represent the people of the 15th Congressional District in November,” said Democratic Congressional Campaign Committee spokesman Evan Lukaske.

Dent said he anticipated supporting a Republican to succeed him. “There will be serious, credible candidates announcing,” he said.