Facing a tough re-election fight in November, Rep. Ryan Costello, R-Pa., added his name on Sunday to a growing list of Republican incumbents bowing out of the midterm elections.
In an interview on MSNBC's "Kasie DC," Costello partly attributed his decision to a state Supreme Court ruling in January that found the Republican-drawn congressional map unconstitutional.
Costello, who was elected in 2014 in a district that includes suburban Philadelphia, also said his decision was motivated by intense opposition from the left and Republicans angered by his disagreements with President Donald Trump.
"The combination of what I've had to deal with, just in terms of having a young family, [with] what the state Supreme Court did — which I think was obscene — along with the political environment has me led me to the decision," he told host Kasie Hunt. "It's been a very tough decision for me to make, but I think I'm making the right decision."
In a 4-3 decision, the Democratic-controlled court ruled in January that the Pennsylvania's congressional boundaries "clearly, plainly and palpably" violated the state's constitution.
Political observers have said the redrawn map — created by Stanford University Law Professor Nathaniel Persily — will likely help Democrats pick up seats in November.
In a statement, National Republican Congressional Committee Chairman Steve Stivers said Costello's retirement was a "great loss."
"We will work tirelessly to ensure this seat remains in Republican hands," Stivers said.