Democratic congressional candidate David Trone greets voters at South Hagerstown High School. (Bill O’Leary/The Washington Post)

Republican congressional candidate Amie Hoeber greets voters in Potomac. (Bill O’Leary/The Washington Post)

David Trone, the Potomac wine magnate who forged a second career as a politician, on Tuesday won the race to succeed Rep. John Delaney in Maryland, culminating a quest that he financed with millions from his vast personal fortune.

In defeating Republican Amie Hoeber, Trone, 62, a Democrat, joins the ranks of Congress’s wealthiest members, having used the money he made as the co-owner of a national chain of liquor stores to overwhelm his opponents and build a political brand.

By Election Day, Trone, who co-owns Total Wine & More, had invested nearly $16 million of his own money in the race, exceeding even the amount he spent two years ago in his first attempt to join Congress.

“We never back down,” Trone told his supporters Tuesday night, promising to find progressive “solutions to big problems.”

“Now is the time we’ve got to pull together as Democrats and Republicans together,” he said. “If we don’t pull together, we won’t be able to move the country forward.”

As was the case when he lost the 2016 Democratic primary for a neighboring House district, Trone’s opponents this year — the Democrats he defeated in the primary and then Hoeber in the general election — portrayed him as trying to buy the seat representing a gerrymandered swath stretching from Montgomery County to Western Maryland.

Instead of responding to the criticism, Trone kept spending his money and repeating pledges to be a counterbalancing voice to President Trump. Along the way, he won over skeptical Democrats, including his opponents in the primary. He won nearly 60 percent of the vote Tuesday, according to unofficial returns, beating Hoeber by a wide margin even as Republican Gov. Larry Hogan cruised to reelection.

“I want the Democrats to take the House, and Trone is a Democrat,” said Stanton Gildenhorn, a Montgomery County Democrat, explaining his support for the businessman whom he opposed in the primary. “The issue I had with him in the primary was the expenditure of his own money. I thought that was outrageous. That’s over. Now the main aim is to take back the House. You don’t unless you vote for Democrats.”

A Hagerstown voting site on Tuesday. (Bill O’Leary/The Washington Post)

The campaign to succeed Delaney, a three-term Democrat who gave up his seat to run for president, was widely viewed as the most competitive of Maryland’s House contests. In another race in eastern Maryland, Rep. Andy Harris (R) easily defeated a spirited challenge from Democrat Jesse Colvin, a former Army intelligence officer.

Sen. Benjamin L. Cardin (D), facing nominal opposition, coasted past his three opponents. The rest of the Democrats in Maryland’s congressional delegation — Reps. Steny H. Hoyer, Anthony G. Brown, Jamie B. Raskin, C.A. Dutch Ruppersberger, John Sarbanes and Elijah E. Cummings — also cruised to reelection. With Democrats back in control of the House, Cummings is expected to chair the House Oversight Committee.

At the polls Tuesday, numerous 6th District voters said they were supporting Trone because he’s a Democrat, even if they were turned off by the businessman’s campaign spending.

“I think you’ve got to send a message that Republicans didn’t stand up to the president,” said Steve Solomon, 61, a lawyer who lives in Potomac and who said he was “unhappily” voting for Trone. “They did not hold him accountable.”

Jack Havas, 75, a business owner and a registered Democrat, said that he would vote a straight Democratic ticket no matter how impressive Hoeber was as a candidate. “That woman could have been the best person ever and I wouldn’t have voted for her because we need to win the House,” he said.

But Sandra Wine, a Potomac resident who described herself as in her 70s, said that Trone’s money pushed her to support Hoeber. “I thought, ‘How come he has so much money he can send me so much literature,’ ” she said of Trone’s mailers. “I felt there was something funny going on.”

In reaching into his personal fortune to win office, Trone joins a club that includes Michael R. Bloomberg, who spent $74 million to become New York’s mayor in 2001; and Jon S. Corzine, who spent $60 million to capture a U.S. Senate seat in New Jersey in 2000.

Before his emergence as a candidate, Trone was a well-known donor to Democratic and Republican campaigns around the country, and he hosted fundraisers at his home for the likes of President Barack Obama and Hillary Clinton.

But his vast resources did not guarantee success. In 2016, he lost the Democratic primary to Raskin in the 8th District despite putting $13 million of his own money into the race and outspending Raskin by a margin of 6 to 1.

John Willis, a University of Baltimore political science professor, said no individual candidate in recent memory in Maryland has spent personal funds as Trone has in the past two election cycles.

Altogether, Trone invested nearly $30 million in the two ­races, according to the most recent campaign finance reports.

“The scale is extraordinary,” Willis said. “It’s a bother to people who are concerned about the fact that the average wealth of an average congressman is greater than the constituents’. I think it’s a problem for policy and the mechanics of how you run. I don’t expect it to become the norm in Maryland.”

Paul Ellington, Hoeber’s campaign manager, said during the race that Trone’s finances made him a formidable opponent for Hoeber, a national security consultant and former Reagan administration official.

Yet Hoeber’s husband, Mark Epstein, a Qualcomm executive, gave more than $1 million to two political action committees that advocated on Hoeber’s behalf, paying for mass mailings that sought to tarnish Trone. Hoeber’s 2018 campaign was her second attempt to win Delaney’s seat. Two years ago, Epstein gave $4 million to a PAC promoting her candidacy.

In his second race for Congress, Trone targeted Delaney’s 6th District seat, outspending by a wide margin the seven opponents he faced in the Democratic primary. Casting himself as a pragmatist, Trone pledged to work with Republicans to find ways to combat opioid addiction, an affliction that claimed the life of his nephew.

The day before winning the nomination in June, Trone learned that he had cancer, a diagnosis that he did not reveal until two months later after undergoing chemotherapy and just before going into the hospital for surgery.

For a couple of weeks, Maryland political circles were rife with chatter that perhaps he would have to fold his campaign. But three weeks after surgery, Trone declared himself “cancer free” and returned to the campaign trail.