Incumbent April McClain Delaney, David Trone, and six others are running in the Democratic primary to represent Maryland's 6th Congressional District on June 23. McClain Delaney and Trone are leading in endorsements and fundraising.

Trone represented the district from 2019 to 2025. In 2024, he did not run for re-election and instead ran in the Democratic primary for U.S. Senate, losing to Angela Alsobrooks 53.4%-42.8%. Trone endorsed McClain Delaney as his successor for the 6th District, and she was elected in 2024 with 53% of the vote. McClain Delaney's husband, John Delaney (D), represented the district from 2013 to 2019.

Inside Elections' Nathan Gonzales writes, "With Trone’s deep pockets and McClain Delaney being an incumbent, the 6th District could end up being one of the most expensive House primaries in the country." Founder of Total Wine & More, Trone has self-financed his campaigns. In his 2024 Senate campaign, he spent more than $61 million. In his initial election to the House in 2018, he spent more than $18 million. St. Mary’s College of Maryland professor Todd Eberly writes, "I think [Trone] really wants that seat back, and I think he’s probably going to be willing to spend whatever is necessary to do that."

McClain Delaney has also self-financed her campaigns but to a lesser extent than Trone. In 2024, she spent roughly $4 million on her campaign for the House. Where Trone outpaces McClain Delaney in fundraising and spending, McClain Delaney does the same in endorsements. As of March 31, her notable endorsements included: Sen. Chris Van Hollen (D-Md.), Maryland Gov. Wes Moore (D), Rep. Nancy Pelosi (D-Calif.), Rep. Sarah McBride (D-Del.), and every Democrat in the Maryland U.S. House delegation. Trone's notable endorsements included state and local officeholders, including Maryland Senate Majority Leader Nancy King (D).

Trone is campaigning to the left of McClain Delaney. He criticizes her vote in support of the Laken Riley Act, a law that allows the detention of individuals residing in the country without legal permission who are accused but not convicted of crimes. Trone says, "I’ve fought politicians who use their office for self-interest, defended women’s access to abortion, and have been unequivocal in my support of immigrant families in the face of Republican attacks. We can’t have any Democrats in Congress siding with Trump and MAGA Republicans. This is the moment to rise and fight. And that’s why I’m running."

McClain Delaney says, "Now, David Trone says I should step aside, so he can have his old office back after he ran for the Senate, lost, and has been sitting on the sidelines. He's a distraction. This race isn't about one man's ego. ... And as a member of team Maryland, I forged strong relationships with Governor Moore and the entire federal delegation, as well as with local leaders across the district." She adds, "On behalf of my district, I stand up to bullies. That’s why I’ll continue to take on Trump’s assault on our government workers, defend our diverse community, protect choice and women’s reproductive rights, and work against inflation-creating tariffs."

According to Maryland Matters and The Washington Post, the 6th District is one of the "least-Democrat-friendly congressional districts in the state," with Democrats winning "there by tighter margins than in the state’s other congressional districts." As of March 31, Republicans controlled the U.S. House 217-214 with one independent and three vacancies.