Unlike endangered Senate Democrats in deeper-red states, Mr. Brown, 65, has opposed virtually all Republican-backed policies in Congress, including a new measure loosening bank regulations that is supported by a dozen Democratic senators. Outside of trade, Mr. Brown said in an interview, he sees no evidence that Mr. Trump “stands with workers.” But the senator mainly fixed his criticism on a specific target — “interest groups and Wall Street influences in Washington.”
“The Republican establishment has captured the government,” Mr. Brown said. “When it comes to what they’re really trying to do every day, it’s the bidding of the billionaire Republican establishment — of Wall Street, of the drug companies, of the gun lobby.”
Both national parties have a great deal at stake in Ohio. For Republicans, the 2018 elections are a test of their ascendancy across the Midwest, and whether Mr. Trump’s appeal to working-class white voters might lift others on the right. He carried a majority of union households in Ohio, sundering the on-and-off alliance of African-American voters with white union members that has periodically delivered the state to Democrats.
Ohio Republicans are fielding a formidable if somewhat ungainly ticket, mimicking the national partnership of old-school Republicans and Trump-style insurgents. The state party has backed Mike DeWine, a low-key former senator who is Ohio’s attorney general, for governor, and Representative Jim Renacci, a more combative Trump ally, for Senate. Mr. Renacci, a wealthy auto dealer, had been battling Mr. DeWine for the nomination for governor, but switched to the Senate race after an appeal from the White House.
Among national Democrats, Ohio is an urgent priority for reasons both symbolic and practical. Victories in 2018 could help them contest the state in 2020, and winning the governorship could give Democrats a hand in the drawing of congressional maps. Prominent Democratic leaders are already sketching out visits. Ms. Warren has raised money with Mr. Brown and plans to campaign for Mr. Cordray, and former Vice President Joseph R. Biden Jr. has committed to hosting a fund-raising event for Mr. Brown soon, and will campaign extensively in Ohio next fall, people briefed on their plans said.
For Democrats like Ms. Warren and Mr. Biden, the state is an inviting arena to deliver a more pointed message on economic inequality than the one Democrats are likely to deploy in the areas most crucial to control of the House. In their quest to pick up 24 seats, congressional Democrats have focused heavily on courting moderate, suburban voters who dislike Mr. Trump, and for whom issues like trade and union rights are remote considerations.
But Michael Podhorzer, political director of the national A.F.L.-C.I.O., said that in Ohio, Democrats’ paramount goal had to be reversing the lurch of working-class whites toward the Republican Party. He said union members have edged away from Mr. Trump in polling conducted by labor groups, but Democrats must overcome skepticism that they “are real on populist issues.”
“It’s a state that is very suspicious of Democrats on economic issues,” Mr. Podhorzer said. “How things turn out is going to be a real indicator of whether Ohio’s going to be a battleground state in 2020.”
Democrats’ determination to reassemble a blue-collar coalition was on display recently in Lorain, a once industrial town about 30 miles west of Cleveland, where Mr. Cordray, 58, pitched himself to a crowd of labor officials arrayed in wooden chairs in a fluorescent-lit hall. Mr. Trump fought Mrs. Clinton to a draw in Lorain County in 2016; President Barack Obama carried it by about 15 points in 2012.
Introduced to the crowd as a warrior against Wall Street, Mr. Cordray called the governorship a platform to “fight back for working people” and pledged to battle the Republican-controlled Legislature on union rights and defend Ohio’s still-contested Medicaid expansion. In an interview, he said Democrats had erred in 2016 by allowing themselves to be seen as a party of the status quo.
“People do want somebody who will fight for them,” said Mr. Cordray, who vowed to compete not just in big cities, but also in the “middle-sized towns around Ohio where they feel things moving gradually away from them and nobody seems to care.”
A soft-spoken lawyer, Mr. Cordray acknowledged that he had to reintroduce himself to Ohio after seven years in the Obama administration. In a sign of his campaign’s national import, Mr. Cordray met with Mr. Obama in Washington late last fall, after stepping down from the consumer bureau. Mr. Cordray said the former president had been “encouraging” of his campaign.
Mr. Obama has not yet issued an endorsement, and while several Democrats have dropped out of the race to back Mr. Cordray, he must overcome a rowdy set of Democratic rivals in a May primary election. The former Representative Dennis Kucinich, 71, a freewheeling firebrand who has aligned himself at times with both Mr. Trump and Senator Bernie Sanders of Vermont, appears to be his most nettlesome foe.
Republicans, however, are girding for Mr. Cordray. Mr. DeWine, still facing a challenger on the right, has begun swiping at Mr. Cordray, lumping him with a cadre of Democrats that he says mismanaged the state. Wagering that Ohioans are mostly happy with the state’s direction, Mr. DeWine is presenting himself as a steady hand.
“We can’t go back to the days of Ted Strickland and Richard Cordray,” Mr. DeWine warned last month at a local party dinner in Clinton County, northeast of Cincinnati, linking Mr. Cordray with an unpopular former governor.
But Mr. DeWine, 71, also allowed in an interview that Ohioans remain restless even after years of Republican dominance. “There’s still a feeling of dissatisfaction, I think, with government,” he said, adding that the mood had helped elect Mr. Trump.
Whether Mr. Trump can again bend that dissatisfaction to Republicans’ advantage could seal their prospects in Ohio. In the Senate race, Mr. Renacci, 59, has staked his campaign on his relationship with the president and attacked Mr. Brown for opposing Mr. Trump’s tax cuts. Both he and the president, Mr. Renacci said in an interview, “want to make sure Ohio is great again.”
But the tangled lines of populist politics could complicate that blunt partisan argument: Where Mr. Brown endorsed the Trump tariffs, Mr. Renacci has been more equivocal, calling them a work in progress.
At a union hall in Dayton last month, Mr. Brown found an audience seemingly friendly both to Mr. Trump and his own campaign. Addressing a Teamsters local about the union’s pension crisis, Mr. Brown was introduced by a pair of labor activists who borrowed from the president’s message to suggest Washington had overlooked them in favor of other vulnerable groups. “We’re dreamers, too,” declared Rita Lewis, a prominent Teamsters activist who is close to Mr. Brown. “We’re not illegal aliens. We’re American citizens.”
Mr. Brown addressed the group in a confiding tone, hunched over a lectern and upbraiding Washington for siding too often with banks over workers. As Mr. Brown worked the crowd afterward, Greg Thompson, a Teamsters member from Akron, explained that he voted for Mr. Trump because of his stance on trade, but these days considered Mr. Brown a more reliable ally.
“I don’t know what to think of the president,” said Mr. Thompson, 69. “He talks out of both sides of his mouth.”
As for Mr. Brown, Mr. Thompson said, “We’re 100 percent behind him.”
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