WASHINGTON — Senator Michael B. Enzi, Republican of Wyoming, said on Saturday that he would not seek re-election at the end of his term, the third Republican senator to do so ahead of the 2020 campaign.



Mr. Enzi, 75, who leads the Senate Budget Committee, has held his seat since 1997, making him the longest-serving Wyoming senator in modern times. Speaking at a news conference in his home state, he said he planned to spend the rest of his tenure focusing on budget overhaul.

“I have much to get done in the next year and a half,” Mr. Enzi said. “I want to focus on budget reform to get control of our national debt.”

“I don’t want to be burdened by the distractions of another campaign,” he added.

Senator John Barrasso, Republican of Wyoming, praised Mr. Enzi’s time in the Senate, calling him a “respected moral leader.”