(Reuters) - Republican Pennsylvania Congressman Ryan Costello announced Sunday that he will not seek re-election in November, boosting Democratic Party hopes of taking another seat, officials said.

FILE PHOTO: Rep. Ryan Costello (R-PA) speaks with the media following a meeting of the Republican conference ahead of the release of their tax reform plan on Capitol Hill in Washington, U.S., November 2, 2017. REUTERS/Aaron P. Bernstein

Costello’s announcement comes on the heels of a Democrat upset in a special congressional election March 13, in an area handily won by U.S. President Donald Trump in 2016, prompting Republicans to sound alarm bells of more possible Democrat wins.

In that race, Republican Rick Saccone conceded his loss to Democrat Conor Lamb on March 21 in the razor-close race for the state’s 18th Congressional District, a Republican stronghold.

Costello announced Sunday to Kasie Hunt, on the MSNBC program Kasie DC, that he will not seek re-election, citing both the redrawn suburban-Philadelphia district that now favors Democrats and his desire to spend more time with his family.

“It’s the most difficult decision I can recall having to make,” he told Hunt on Sunday night. “I have an 8-month-old. I have a 4-year-old. And it’s a very challenging job, serving in Congress with a young family.”

National Congressional Campaign Committee Chairman Rep. Steve Stivers told ABC News that Costello’s retirement is a “great loss.”

He said in a statement to the news agency, “We will work tirelessly to ensure this seat remains in Republican hands.”

The Democratic Congressional Campaign Committee said in a statement that other Republicans 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 in a press release.

Neither Costello nor his representatives were immediately available for comment.