COLUMBUS, Ohio — Sherrod Brown won seven terms in the U.S. House and two terms in the Senate by campaigning against “job killing” international trade deals. He has prodded presidents from both parties over their support for NAFTA, CAFTA and expanded trade with China. But he has never, in nearly 25 years in Washington, actually won a congressional battle over a major trade agreement.

This year, it looks like that losing streak will end.

The politics of globalization have swung quickly and decisively in favor of Brown and his populist allies. A massive trade deal is close to death in Congress. Washington’s long-running romance with freer trade is on the rocks.

That’s partly due to the battle Brown and like-minded lawmakers have waged against trade agreements for decades. And it’s partly due to Donald Trump: His core supporters, like the union-proud Democrats who love Brown, have rebelled against trade deals, and many Republican politicians have followed their lead.

A bipartisan surge of grass-roots anger, over lost jobs and displaced workers, has driven the shift.

Sunday’s presidential debate will likely highlight how opposition to trade deals has become the safe position for a Democratic or Republican presidential hopeful. Trump and Democrat Hillary Clinton focused much of their economic discussion at the first debate on trade, with both coming out hard against the Trans-Pacific Partnership agreement now languishing in Congress.

The TPP, as it is known, is a 12-nation trade deal negotiated and pushed by the Obama administration. The Senate majority leader, Mitch McConnell (R-Ky.), said recently that it will not get a vote this year.

If that proves true, and TPP fails to pass in the lame-duck session after the election, advocates on all sides agree the next president is almost certain to let it die in its current form. That is true of Trump, and signs — public and private — point to it being true for Clinton, despite Trump’s repeated claims that she would embrace the TPP if elected.

“We’re winning on TPP,” Brown said, sounding more optimistic on a trade fight than he has in 10 years of interviews with this reporter. “The country already was there. It’s just the elected officials and candidates are catching up.”

Most Americans probably would not notice an immediate effect if the deal fails. Supporters predict it would boost economic growth (a claim challenged by critics), but only by a modest amount over the next decade.

When Brown, Ohio’s perpetually rumpled senior senator, first ran for his seat in 2006 on a trade-centered platform, several Democratic strategists privately warned the issue couldn’t move voters in a statewide race. A decade later, both Clinton and Trump are centering their pitches to the swing-state’s middle-class voters on opposition to trade, in speeches that often sound directly sourced from Brown’s playbook (“Myths of Free Trade”).

This comes as concerns, in both parties, are growing about the health of America’s middle class, and with the mounting struggles of large business groups to push some of their top economic priorities, including the TPP, through Congress.

“You’ve got a whole political party now that’s willing to think and talk about it, that’s changed it,” Brown said, speaking of Republicans. Washington Democrats, he added, have gone from “2 to 1 against, to now, four, five, six to one, against these trade agreements.”

Polls can send conflicting messages on how Americans view trade deals, but they tend to show a few clear trends in recent years. New data out this week from the Chicago Council on Global Affairs are a good example. They show Democrats have grown more supportive of trade, as it affects the U.S. economy broadly, during the Obama years. Republicans have grown less supportive.

But the survey also shows majorities in both parties remain deeply critical of trade as it pertains to American workers. Just 2 in 5 Americans agree that trade has been good for creating U.S. jobs. Only about 1 in 3 say it has been good for Americans’ job security.

Those concerns appear to weigh heavily on presidential primary voters. Clinton fended off her primary opponent, longtime trade critic Bernie Sanders, in part by diving into specific critiques of parts of the TPP agreement, a strategy her aides say helped her win the Ohio primary.

While a shrinking pool of centrist Democrats maintain hope that Clinton would reverse course and support the agreement if she won the White House — especially since she once supported it in early stages, when she was secretary of state — she and her closest advisers are emphatic: She will not flip.

Brown has criticized Obama and former president Bill Clinton on trade, and he appears willing to stake his trade legacy on Hillary Clinton breaking from them as president. “I’m certain of it,” he said. “She understands these issues. We’ve talked about them. She understands them in depth, and she feels them.”

Trump’s central economic message through the primaries and the general election campaign has been to threaten tariffs against China, Mexico and other trading partners and promise to return millions of manufacturing jobs to the United States by renegotiating trade deals. His advisers say such moves would reduce America’s trade deficit and increase economic growth; meanwhile, a recent survey of top economists found that none of them believed tariffs would be good for the economy.

“We will win this election,” Trump told an Ohio crowd in August, “and we will keep America out of the TPP.”

David B. Cohen, a political-science professor at the University of Akron and longtime observer of Ohio politics, said it is “shocking” to see how a Republican candidate “has essentially co-opted what traditionally is a progressive Democratic issue.” But the timing, he added, is no surprise: “A lot of voters, especially in Rust Belt states, a lot of blue collar workers, feel left behind.”

Ohio lost more than 400,000 factory jobs from the late 1990s through the depths of the Great Recession, before regaining 75,000 of them in the current recovery. Many Ohio politicians have long blamed trade for many of those losses.

A Democratic congressman, Tom Sawyer, lost his seat in 2002 after voting in favor of the North American Free Trade Agreement. Brown unsuccessfully fought that agreement, NAFTA, as a freshman congressman. He also fought against the Central American Free Trade Agreement and agreements with individual countries, such as South Korea.

Brown used trade to pummel his incumbent Republican opponent, Mike DeWine, in the 2006 campaign that vaulted him to the Senate. Many Democratic strategists in the state privately worried the strategy would backfire. DeWine was eager to attack Brown on the issue, particularly the importance to Ohio companies of exports.

“Sherrod thinks you can build a wall around the state of Ohio,” DeWine said in a debate televised live on NBC’s “Meet the Press” that October. He added: “When it comes time to protect Ohio industries, he’s not there.”

Pro-trade Democrats have long learned not to try to sway Brown on the issue: “If you’re depending on having Sherrod Brown’s vote on a trade deal,” said Jim Kessler, of the centrist Democratic think tank Third Way, “you don’t have a theory of winning.” But he has sometimes frustrated the Obama administration on trade, and Obama has frustrated him.

In Ohio’s 2008 Democratic presidential primary, both he and Clinton pledged to renegotiate NAFTA. During that primary, Brown was upbeat: “The winner, Hillary or Barack, will come to Congress [as president] with a different trade policy,” he said in a 2008 interview. “They’ll follow through.”

Instead, Obama disappointed Brown and other trade critics, by pushing the TPP agreement as a capstone economic and diplomatic achievement. The agreement appeared headed for a narrow victory after Obama won “fast track” trade authority from Congress last year. But then came the primaries, and the rise of Sanders and Trump, and Clinton’s hardening line against the agreement.

The margins for TPP are thin: the fast-track measure cleared the House by just 10 votes last year, with only 28 Democrats supporting it. Since then several Republicans have reversed course and said they would oppose the final agreement.

“It’s still alive. It’s not easy, but then again, I can’t remember a trade vote that’s been easy,” said Linda Dempsey, vice president of international economic affairs for the National Association of Manufacturers. “Everybody who wants to get this done believes lame duck absolutely is the best opportunity.”

Obama has pushed the pact in order to embed America more firmly in the world’s fastest-growing and most populous region, and to counter the growing regional influence of China. On a tour of Asia recently, he told reporters that “I believe [the TPP] will be ratified because it’s the right thing to do” but acknowledged the political difficulties. “We’ll have to cut through the noise once election season is over,” he said.

Dempsey and several other trade advocates see little hope that Clinton or Trump would move the agreement as president. Obama “took a trade-skeptical position in 2008 under the same pressures [Clinton] is facing,” said Will Marshall, the president of the centrist Progressive Policy Institute in Washington. “But they weren’t as intense then as they are now. There’s a populist, anti-globalist fever spreading.”

That spread is both a vindication for trade-deal opponents, particularly organized labor leaders, and also a threat to the Democratic candidates they traditionally support. Union leaders have blanketed Ohio this election season, holding news conferences to denounce Trump as a fraud on the issue, largely because his own companies have frequently outsourced production work to other countries.

Brown is more brutal on Trump’s trade stance — “he has no understanding of it, no depth on it, is a hypocrite about it” — and optimistic that 2016 will prove a tipping point on the issue.

After all, so much else appears to be swinging his way. In June he saw a Cleveland sports team, the Cavaliers of the National Basketball Association, win the town’s first professional championship since 1964. He believes the city’s baseball team, the Indians, will win the World Series this month. And then a Clinton win, he predicts, and the defeat of TPP.

“This year,” he said, “is really going to be the year.”