Rep. Ryan Costello (R-Pa.), pictured during a mock swearing-in ceremony in 2017, said the new congressional district map in the state played a factor in his decision. | Zach Gibson/AP Photo Rep. Costello won’t run for reelection in Pennsylvania

Republican Rep. Ryan Costello won't seek reelection this fall, a blow to Republicans seeking to hold his redrawn, suburban Philadelphia district.

In an interview on Sunday with the Daily Local News of West Chester (Pa.), Costello blamed the "political environment" for abandoning his reelection bid, including the conduct of President Donald Trump.


“Whether it’s Stormy Daniels, or passing an omnibus spending bill that the president threatens to veto after promising to sign [it], it’s very difficult to move forward in a constructive way today,” Costello told the newspaper.

Costello also had blame for "the left" for contributing "a lot of hate" and fostering a toxic political environment.

“In some respects, my ego says to run," he added. "But when I look at what is the right decision for those who rely on me and the state of our body politic, I am convinced that no matter how bipartisan and open and transparent I am, there is so much anger out there that it doesn’t matter.”

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But Costello's decision is also a reflection of a changed political reality in Pennsylvania. His battleground congressional district was made more Democratic-leaning when the state Supreme Court drew new House districts earlier this year. Under the new lines, Hillary Clinton carried the district in 2016, 53 percent to 43 percent, even as she lost statewide. Clinton won the district by only a single point under the old lines.

In a separate interview with MSNBC, Costello acknowledged that the new map played a role in his decision not to run again.

"What happened was the state Supreme Court then, in a matter of a week or so, decided to invalidate the map — the first time in the history of the republic where a state supreme court has done that and ultimately altered the district," he said.

Costello filed for reelection last week, but he has until Tuesday to withdraw from the race so that his name does not appear on the May 15 primary ballot. He told the Daily Local News that he will confer with local party officials about whether he will remove his name from the ballot.

If he does officially withdraw in the next 48 hours, attorney Greg McCauley would be the only GOP candidate for the nomination. But if Costello remained on the ballot and defeated McCauley for the nomination, he could be replaced on the ballot by local and state Republicans.

The Democratic front-runner is Chrissy Houlahan, a military veteran who ended last year with more than $950,000 in campaign cash on hand.