GOP Rep. Ryan Costello to retire, boosting Democratic hopes of taking his House seat Rep. Ryan Costello's retirement may open the door for Democratic hopefuls.

Rep. Ryan Costello, R-Pa., will not seek re-election this year, ABC News has confirmed, a move that boosts Democrats’ chances of winning his House seat.

Costello cited a number of factors in his decision, including the newly-redrawn map of House seats in Pennsylvania that made his district more Democratic and the current political climate.

“Whether it’s Stormy Daniels or passing an omnibus spending bill that the president threatens to veto after promising to sign, it’s very difficult to move forward in a constructive way today,” he said, referring to the former porn star who claims she had an affair with Donald Trump.

Under the new congressional map, Costello’s 6th Congressional District was transformed from one that Hillary Clinton won by one point in 2016 to one she would have won by nine points under the new lines.

Republicans in the state had fought to get a stay on the new map, which had been legally ordered by the Pennsylvania Supreme Court. But last week the U.S. Supreme Court denied their appeal, locking the new map into place.

Democrats see this seat as one they could pick up in their quest to win 23 seats in order to take back control of the House. Their candidate, Chrissy Houlahan, is an Air Force veteran who was endorsed by former Vice President Joe Biden a few weeks ago.

“While Congressman Costello and I might have disagreed on many issues, I respect and thank him for his service to our country, Commonwealth, and community,” Houlahan said in a statement Sunday night. “I wish him and his family well in this new chapter of their lives. My campaign is just getting started. I look forward to continuing to travel throughout our district to listen to all of the people in our community.”

Costello is not saying at this time if he will remain on the ballot through the May 15 primary election. The filing deadline was March 20, and an unknown candidate, attorney Gregory Michael McCauley, also filed on the GOP primary ballot.

If Costello formally withdraws before the primary election, McCauley would be the GOP nominee. If Costello stays on the ballot, wins the primary and then withdraws, the Pennsylvania Republican Party could name a replacement candidate.

Costello said he would consult with party officials before deciding on when to formally withdraw.

National Congressional Campaign Committee Chairman Rep. Steve Stivers said Costello's retirement is a "great loss."

"We will work tirelessly to ensure this seat remains in Republican hands," he said in a statement.

The Democratic Congressional Campaign Committee said other Republicans in swing districts should take heed of Costello’s decision.

“Costello's exit should set off alarm bells for vulnerable House Republicans, who will also have to explain to middle-class voters why they’ve given repeated handouts to the rich and biggest corporations, and who will face similarly tough, well-financed challenges from our deep field of impressive candidates,” said spokesman Evan Lukaske.

Pennsylvania’s Republican delegation in the House is losing a lot of incumbents this year.

Rep. Tim Murphy resigned after a scandal; Rep. Lou Barletta is running for Senate; and Reps. Bill Shuster, Charlie Dent and Patrick Meehan are also retiring.