MADISON, Wis. (AP) — U.S. Rep. Mike Gallagher, a key Republican Congressman who has spearheaded House pushback against the Chinese government, announced Saturday that he won’t run for a fifth term. The announcement comes just days after he angered his fellow Republicans by refusing to impeach Homeland Security Secretary Alejandro Mayorkas.

The GOP has been looking to oust Mayorkas as a way to punish the Biden administration over its handling of the U.S.-Mexico border. A House impeachment vote Tuesday fell just one vote short. Gallagher was one of three Republicans who opposed impeachment. His fellow Republicans surrounded him on the House floor in an attempt to change his mind, but he refused to change his vote.

Record numbers of people have been arriving at the southern border as they flee countries around the globe. Many claim asylum and end up in U.S. cities that are ill-prepared to provide for them while they await court proceedings. The issue is potent line of attack for Donald Trump as he works toward defeating President Joe Biden in November’s elections.

Gallagher wrote in a Wall Street Journal op-ed published after the vote that impeachment wouldn’t stop migrants from crossing the border and would set a precedent that could be used against future Republican administrations. But the impeachment vote’s failure was a major setback for the GOP. Wisconsin Republicans began mulling this week whether Gallagher should face a primary challenger.

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Gallagher did not mention the impeachment vote in a statement announcing his retirement, saying only that he doesn’t want to grow old in Washington.

“The Framers intended citizens to serve in Congress for a season and then return to their private lives,” Gallagher said. “Electoral politics was never supposed to be a career and, trust me, Congress is no place to grow old. And so, with a heavy heart, I have decided not to run for re-election.”

He told the Milwaukee Journal Sentinel that the backlash over the impeachment vote did not play a role in his decision.

“I feel, honestly, like people get it, and they can accept the fact that they don’t have to agree with you 100%,” he told the newspaper, adding later in the interview: “The news cycle is so short that I just don’t think that stuff lasts.”

Voicemails The Associated Press left at his offices in Washington and Wisconsin on Saturday weren’t immediately returned.

Gallagher, a former Marine who grew up in Green Bay, has represented northeastern Wisconsin in Congress since 2017. He spent last year leading a new House committee dedicated to countering China. During the committee’s first hearing, he framed the competition between the U.S. and China as “an existential struggle over what life will look like in the 21st century.”

Tensions between the two countries have been high for years, with both sides enacting tariffs on imports during Trump’s term as president. China’s opaque response to COVID-19, aggression toward Taiwan and the discovery of a possible spy balloon floating across the U.S. last year have only intensified lawmakers’ intent to do more to block the Chinese government.

Chinese officials have lashed out at the committee, accusing its members of bias and maintaining a Cold War mentality.

Gallagher was one of the highest-profile Republicans considering a run for U.S. Senate this year against incumbent Wisconsin Democrat Tammy Baldwin. But he abandoned the idea in June. He said then that he wanted to focus on countering China through the committee and that he planned to run for a fifth term in the House.