WASHINGTON — It is quite a testament to the current state of the Senate that a successful veteran lawmaker of two decades believes he can accomplish more by quitting than by trying to stick it out another six years.
“This place is definitely broken,” said Senator Tom Udall, Democrat of New Mexico and a longtime advocate of government reform who surprisingly announced in March that he would not seek a third term in 2020 in his solidly blue state.
In assessing his political future, Mr. Udall said he had become convinced that he could do more to advance his progressive ideas on climate change, war powers and a comprehensive electoral overhaul by skipping another two years of relentless re-election fund-raising. Instead, he said, he intends to redouble his efforts in those areas in hopes of setting the stage for big changes should Democrats prevail next year, even though he won’t be back in the Senate himself.
“You don’t necessarily have to be there to see that they are completed,” he said.
Mr. Udall’s decision to not run again, discussed in an interview on Wednesday, showed how the gridlock infecting Congress and the wide political divisions in the country can frustrate even the most experienced lawmakers and make them rethink their careers. It also illustrates how overwhelming and time-consuming fund-raising for multimillion-dollar races can be, leaving lawmakers little opportunity for the work they are supposed to be doing.
When he announced his own retirement this month, Senator Michael B. Enzi, a 75-year-old Wyoming Republican who is the chairman of the Budget Committee, said he would rather spend his remaining time in the Senate working on budget issues than campaigning.
A member of a storied Western political family, the usually understated Mr. Udall expressed real alarm about the direction of the nation’s politics. He said the current strain he saw on governing institutions had him ready to appropriate the “troubled optimist” description that his father, Stewart Udall, who served as the interior secretary in the Kennedy and Johnson administrations, used to apply to himself.
“We really are being stretched to the limit,” said Mr. Udall, who sees President Trump and his allied Republicans as upending the governing norms of the nation. “I am committed to changing the course this president has set for this country.”
Mr. Udall is one of four members of the Senate — and the only Democrat — to so far announce he would not be on the ballot next year, and he sees little hope for advancing much significant legislation in the Republican-controlled Senate. The president’s declaration in recent days that he was not interested in working on bipartisan legislative initiatives as long as Democrats were investigating him probably did not lead Mr. Udall to reconsider his retirement decision.
But not everyone is exiting out of exasperation. Senator Lamar Alexander, the three-term Tennessee Republican who also said he would not seek re-election in 2020, said the partisan tension in the Senate presented a challenge but one that could still be overcome.
“Do I think it could be easier? Yes,” Mr. Alexander said. “Is the environment difficult to work with? Sometimes it is. But I get a lot done, and that requires working with people across the aisle. It takes a lot of patience and it takes people who trust you and you have to trust them, and sometimes you don’t succeed but often you do.”
“I will be 80 years old when I leave,” he said. “I will have served longer as senator and governor than anyone else in Tennessee history, and I think that’s plenty.”
At 70, Mr. Udall is far from old in Senate terms. But he viewed another Senate run as an eight-year commitment, given the need to aggressively campaign, and he did not consider that the best use of his time.
Mr. Udall is an ardent Democrat but, like Mr. Alexander, he has a history and reputation for being able to work in a bipartisan fashion, particularly on environmental issues. In 2016, he defied expectations and struck a deal with David Vitter, then a Republican senator from Louisiana, to renew and update the Toxic Substances Control Act for the first time in 20 years. Yet even that achievement has led to disappointment.
“It is not being implemented,” Mr. Udall said. “The parts of it that protect the public and protect the food are not being put in place.” He blamed the Trump administration and officials at the Environmental Protection Agency for failing to follow through.
“They are chasing off all these people, the scientists and everyone else,” he said of the current administration. “You could have the greatest law in the world but you don’t get it done.”
Mr. Udall has also made restoring Congress’s sole authority to declare war and bringing to a close what he describes as the nation’s “endless wars” a priority, but he has had little success. Last Wednesday, he lost a vote in the Foreign Relations Committee to prohibit any military operations against Iran that were not specifically approved by Congress. The outcome left Mr. Udall fearing that with tensions rising, the United States could conceivably be in a conflict in Iran before Congress returned from its Memorial Day recess to weigh in.
Mr. Udall has been a champion of the Senate version of a comprehensive election and ethics overhaul backed by all Democrats — and deemed a nonstarter by Senator Mitch McConnell of Kentucky, the majority leader — so his decision to leave has distressed watchdog groups. But they, like him, believe he can remain an influential voice outside Congress for what all agree is likely to be an extended fight given the types of sweeping changes they envision.
“I would rather have him in the Senate, but people have to make their personal decisions and sometimes the time comes to do something else and take a different approach,” said Fred Wertheimer, the president of the group Democracy 21, who has worked closely with Mr. Udall for years. “He is not walking away from the issue. He is just changing the playing field for himself.”
Mr. Udall believes he can remain a force on that new playing field, perhaps even a more potent one than if he remained in the limiting confines of the Senate.