Del. Neil C. Parrott (R-Washington County) won the Republican primary Tuesday in Western Maryland’s 6th Congressional District, according to an Associated Press projection, earning the right to take on Rep. David Trone (D) this fall in a seat the GOP is hoping to flip.

Parrott defeated several competitors — including 25-year-old Matthew Foldi, who had endorsements from Gov. Larry Hogan (R) and some national figures — to advance to the general election. Trone, the massively wealthy co-founder of Total Wine & More, is the state’s only vulnerable Democrat heading into the midterm elections, where the party’s slim House majority is on the line.

Trone and a slate of other incumbent Democrats won their own contests Tuesday, according to AP projections, though some races did not yet have projected winners. Among them was the state’s highest-profile matchup, in Maryland’s 4th District, between former congresswoman Donna F. Edwards and former Prince George’s state’s attorney Glenn Ivey.

Edwards and Ivey had been locked in a bitter faceoff that attracted millions of dollars in outside spending. The race became a showcase of the unchecked influence that national special-interest groups can wield in politics, even though voters in the 4th District, anchored in Prince George’s, had indicated they are largely focused on local issues about public safety and gun violence and also the cost of living in a strapped economy.

A new super PAC affiliated with the pro-Israel American-Israel Public Affairs Committee, which endorsed Ivey, spent nearly $6 million against Edwards, flooding the airwaves with ads bashing her constituent services while in office. Edwards sought to overcome those attacks by leveraging her reputation as a four-term liberal congresswoman with backing from House Speaker Nancy Pelosi (D-Calif.), who defended Edwards as “one of the most effective” lawmakers during her time in Congress.

Donna Edwards wants her Md. seat back. Glenn Ivey stands in the way.

The attack ads made an impression on voters — but not always in the way AIPAC or the United Democracy Project might have hoped. Some voters said being bombarded with attack ads on television about Edwards turned them off and seemed unfair, which in turn led them to support her.

Ellen Hughes, of Laurel, said she started to pay more attention to the congressional race after seeing dozens of negative ads targeting Edwards. She was open to learning about both candidates but said Ivey’s reluctance to condemn the negative campaign against his opponent was a breaking point for her.

“He could have said, ‘Stop this,’ but he didn’t,” Hughes said. “I would have listened to both, but now I want nothing to do with Glenn Ivey.”

While Israel policy was never a major focus of the ads, it was still important to some Marylanders on Tuesday. Quinn Dang, a 22-year-old voter in College Park who uses they/them pronouns, said that as they started to do research, they were looking for candidates who had strong liberal credentials.

Ivey and Edwards agreed on many liberal policy stances, including gun-violence prevention and abortion rights. But one key difference stood out to Dang: Ivey’s backing from AIPAC, something Dang considered “nonnegotiable.” When Dang read up on the attack ads funded by the AIPAC-affiliated super PAC, they said, the decision was easy.

“I looked on their sites, and I was like, ‘Okay, Donna Edwards has a record of being of progressive, and she has endorsements from progressive individuals that I trust,’ ” Dang said. “And Glenn Ivey is pro-Israel.”

AIPAC’s opposition to Edwards dates to 2009, in her first term, when she voted “present” on a resolution to support Israel’s right to defend itself from attacks from Gaza. But Edwards retained strong support from the more liberal Israel policy group J Street, which spent more than $700,000 to support her. One of its attack ads against Ivey connected him to AIPAC, pointing out that it also supports Republicans who objected to election results, a link Ivey’s campaign condemned.

Former delegate Angela Angel (D-Prince George’s) and several others were also seeking the nomination for the 4th District seat, which became open because Rep. Anthony G. Brown (D-Md.) decided to run instead for state attorney general.

Maryland’s six other incumbent House Democrats did not face competitive primary challengers Tuesday. House Majority Leader Steny H. Hoyer and Reps. Kweisi Mfume and C.A. Dutch Ruppersberger advanced to their general election races, as did Sen. Chris Van Hollen, according to AP projections.

What you need to know about delayed election results in Maryland

Results in some races may take several days, because Maryland law does not allow election workers to begin counting the state’s hundreds of thousands of mail-in ballots until Thursday. Even then, it could take a few more days or longer for workers to finish hand-counting them, state elections officials have said.

Rep. Andy Harris, the only Republican in the state’s congressional delegation, was unopposed in his 1st District primary. The AP projected Tuesday that former delegate Heather Mizeur won the Democratic primary Tuesday, queuing up a long-shot bid to unseat him. Mizeur, who previously represented Takoma Park but now lives on a small farm on the Eastern Shore, defeated former U.S. Foreign Service officer Dave Harden.

Mizeur had raised nearly $2 million — more than Harris — during the campaign. But while Democrats were eager for a chance to unseat Harris, a staunch Trump ally, their hopes faded after a redistricting legal battle yielded a final congressional map that left the Eastern Shore solidly red.

Explore the major changes to Maryland’s congressional map

Parrott’s projected victory Tuesday, meanwhile, sets up a rematch with Trone, who beat Parrott in 2020 by roughly 20 points. Maryland’s 6th District became much more competitive after redistricting this year, creating an opening for Republicans to flip the seat red under the right conditions. Parrott, however, will have to contend with Trone’s huge campaign war chest. The two-term Democrat has already poured $12 million of his personal money into his campaign, evidence that he isn’t taking any chances this year, despite past criticism that he was “buying” the seat.

Parrott has served six terms in the Maryland House of Delegates, developing a reputation as a combative socially conservative lawmaker and advocate of direct democracy in the state who has taken his crusades to the courts and to the ballot box. Soon after taking office in 2011, Parrott’s public profile rose with the creation of MDPetitions.com, as he led petition drives to repeal laws such as same-sex marriage or in-state tuition for undocumented immigrants, forcing voter referendums on the issues that ultimately failed.

In the courts, Parrott sued Hogan over his pandemic mandates in May 2020 prohibiting large gatherings. More recently, Parrott sued the state over a congressional map that advantaged Maryland Democrats. That lawsuit turned out to be a major victory for Parrott and Republicans, after a judge agreed that Democrats engaged in illegal partisan gerrymandering and ordered that the map be redrawn, resulting in the 6th District’s new, more competitive format.

President Biden still won the district as it’s currently drawn by 10 points in 2020, but rising costs of living and a poor approval rating for Biden have Republicans chattering about a red wave this year.

Md. Republicans love Trump and Hogan. Whose candidate will win Tuesday?

Parrott’s stiffest competitor, Foldi, faced an apparent name-recognition hurdle despite his endorsements.

Pam Beall, a voter who said she came to the polls at Urbana High School in Ijamsville to support conservative candidates opposing abortion and big government, said she voted for Parrott in part because his was the only name she knew.

“I’ve heard about him,” she said, “so that’s who I’m voting for.” Asked whether she knew anything about Foldi, she shrugged and shook her head.

Daniel Larason, a 27-year-old viticulturist, said he had also cast his ballot for Parrott at the high school. Most of the candidates in that primary seemed ideologically similar, but Larason had seen more ads from Parrott than any of his rivals. And in his mind, he said, winning in November was the top priority.

One couple split between Parrott and Foldi, seeing different strengths or weaknesses in each.

Barbara Pfister, 60, went for Foldi, taking a cue from Hogan’s endorsement. “I thought he would bring positive change,” she said.

Her husband, though, thought Foldi was too young. “Not that youth is a detriment,” Bruce Pfister, 63, was quick to add, but “I like experience.” Parrott won him over, he said, with a “very personal” mailer sent to the Pfisters and signed by Parrott’s wife.

Vanessa G. Sánchez, Daniel Wu and Teo Armus contributed to this report, which will be updated.