Republican U.S. Rep. Jim Hagedorn announced Wednesday that he's being treated for Stage 4 kidney cancer.

The 57-year-old congressman, who represents southern Minnesota's First District, said he received the diagnosis in February 2019 and has been undergoing immunotherapy at Rochester's Mayo Clinic over the past year.

The diagnosis will not affect his re-election campaign, he said. Hagedorn faces a tough re-election fight against Democrat Dan Feehan, whom he narrowly defeated by about 1,300 votes in 2018.

"This disease has not and will not deter me," Hagedorn said in a statement. "Exactly two months after marrying my wife … and just six weeks into my job as the First District's congressman, I was given unexpected and rather shocking news. Just like millions of other Americans, I was told by my doctor: You have cancer. After prayers and long talks with those closest to me, I was determined to fight it like hell."

Hagedorn is married to Jennifer Carnahan, the chairwoman of Minnesota's Republican Party. She issued her own statement Wednesday, saying that although "the past year hasn't been easy … we both remain committed to one another, our jobs, our state and our country."

The cancer was detected during a routine physical examination, Hagedorn said, before any symptoms surfaced. The illness has not impeded his congressional work or caused him to miss a vote on the House floor, he said.

"I've been able to do my job, make hundreds of stops across the First District, hold 18 town hall meetings, and make 39 round trips to and from Washington, D.C., to perform my legislative duties," Hagedorn said. "I am fortunate to be a patient of the Mayo Clinic. … I am also grateful for the regimen of immunotherapy, recently approved by the FDA as a treatment for kidney cancer."

Dr. Lance Pagliaro, an oncology specialist at the Mayo Clinic, said Hagedorn has responded well to the treatment, calling it a "key to his recovery."

Hagedorn has remained a steadfast supporter of President Donald Trump throughout his first term in Congress, despite his slim 2018 victory in the swing district he represents. The Blue Earth resident has emerged as a top target for Democrats in 2020, with state and national party groups highlighting votes and public comments he has made that repeatedly put him on the same page as the president.

Hagedorn voted against impeaching Trump on charges of abuse of power and obstructing Congress. He said at the time that Democrats should move past the proceedings and focus on issues such as lowering prescription drug prices, securing the U.S.-Mexico border and rebuilding the nation's infrastructure.

His Democratic foe, Feehan, wished him a "full and speedy recovery" in a Facebook post Wednesday night, as did Minnesota DFL Chairman Ken Martin, who said he was "deeply saddened" to learn about the diagnosis.

"For as long as I've known him, Jim has been a fighter, and I wish him a swift recovery in his battle with cancer," Martin said in a statement.