FILE PHOTO - U.S. Representative Charlie Dent is interviewed during the 2017 "Congress of Tomorrow" Joint Republican Issues Conference in Philadelphia, Pennsylvania, U.S. January 25, 2017. REUTERS/Mark Makela

WASHINGTON (Reuters) - U.S. Representative Charlie Dent, a seven-term moderate Republican from Pennsylvania who has been a frequent critic of President Donald Trump, said on Thursday he would not seek re-election next year.

Dent, 57, said in a statement he made the decision in midsummer not to run and that he had never planned to serve more than five or six two-year terms in Congress.

He lamented the atmosphere in Washington, saying it was plagued by “disruptive outside influences that profit from increased polarization and ideological rigidity that leads to dysfunction, disorder and chaos.”

Dent has opposed Trump, a fellow Republican, on several high-profile issues, including the attempt to repeal the Obamacare healthcare law and the president’s order temporarily banning travelers from six Muslim-majority countries.

He easily won re-election in 2016 but faced a primary challenge next year from Republican state Representative Justin Simmons, a conservative who has branded Dent as “the most liberal Republican in Congress.”

Dent’s district in eastern Pennsylvania voted for Trump in November but backed former Democratic President Barack Obama in 2008.

Dent co-chairs the Tuesday Group of moderate Republicans and has been an outspoken voice calling for bipartisanship in Congress.

(This version of the story removes reference to Obama winning district in 2012)