(The Hill) — Third-term Sen. Bob Casey (D-Pa.), who is up for reelection in 2024, announced Thursday that has been diagnosed with prostate cancer, which he said came as “a shock.”

Casey, who was in Washington on Tuesday to welcome newly elected Sen. John Fetterman (D-Pa.) to the Capitol, said he expects to undergo surgery soon.

“Last month, I was diagnosed with prostate cancer. While this news came as a shock, I can report that I have an excellent prognosis, as well as the benefit of exceptional medical care and the unwavering support of my family,” Casey, who is 62 years old, said in a statement.

Casey is expected to run for reelection to a fourth term in 2024, but he could face a tough race in a competitive swing state, which hosted one of the most expensive and closely watched Senate races of the 2022 midterm election.

Republicans are already talking about a potential challenge from hedge fund CEO David McCormick, who narrowly lost the race for the Senate GOP nomination to Mehmet Oz last year.

Casey said Thursday that he expects to make a full recovery and return to his Senate duties without much of an interruption.

“In the coming months, I will undergo surgery, after which I am expected to make a full recovery. I am confident that my recommended course of treatment will allow me to continue my service in the 118th Congress with minimal disruption,” he said.

Casey’s announcement came shortly after four-term Democratic Sen. Debbie Stabenow (Mich.) announced she will not run for reelection, creating a pick-up opportunity for Republicans in a state that former President Donald Trump carried in 2016.

Senate Democrats will have to defend 23 seats in the next election while Republicans only need to defend 10 and don’t have any obviously vulnerable GOP incumbents.

Sens. Joe Manchin (D-W.Va.) and Jon Tester (D-Mont.), who are up for reelection in two solidly Republican states that Trump won in 2016 and 2020, haven’t said whether they plan to run for reelection.