Maryland Congressional District 8 Democratic primary candidate Kathleen Matthews with her husband, Chris Matthews, host of “Hardball with Chris Matthews" on MSNBC. (Rebecca D'Angelo/for The Washington Post)

Opponents of Maryland congressional candidate Kathleen Matthews are questioning campaign donations she’s received from guests on “Hardball,” the MSNBC talk show hosted by her husband, Chris Matthews.

Three candidates in the 8th District — two of them Democratic primary opponents of Matthews’s and the other a Republican she could face in the general election — say the donations from Washington A-listers raise questions about whose interests Matthews will represent if she wins the April 26 primary and is elected in November.

“This kind of you-scratch-my-back-I’ll-scratch-your-back behavior is exactly what is wrong with Washington today,” Republican Aryeh Shudofsky said. “Chris Matthews has failed to be transparent about the relationship between ‘Hardball’ and Kathleen Matthews’s candidacy.”

Democrat David Trone, the wealthy wine retailer who is self-financing his candidacy as a way of showing he is not beholden to special interests, said through a spokeswoman: “The revolving door of political insiders trading favors with each other is just one reason why so many have lost faith in our political system.”

Both candidates were responding to a report last week in the online news site the Intercept that nearly $80,000 in donations to Matthews came from 48 frequent “Hardball” guests, their spouses or political action committees.

The story, based on Federal Election Commission reports and program transcripts, questioned the timing of the donations and Chris Matthews’s failure to disclose them on the show.

The campaign contributions amounted to $79,050, according to the Intercept, or about 5 percent of the $1.5 million that Matthews — a former WJLA news anchor and Marriott executive — raised through Dec. 31.

None of the candidates who questioned the contributions — Shudofsky, Trone and Del. Kumar P. Barve (D-Montgomery) — accuse the Matthewses of illegal activity. Shudofsky, however, has called on MSNBC to remove Chris Matthews from the air for the duration of Kathleen Matthews’s candidacy.

MSNBC has pushed back hard on the story, picked up in recent days by conservative and mainstream media outlets including the New York Post, the Daily Caller and CNNMoney.

“ ‘Hardball’ has never booked a guest in exchange for a political contribution,” MSNBC spokesman Mark Kornblau said in an email Wednesday night. “That is an offensive accusation that would violate not only the standards of NBC News, but also Chris’ personal ethics.”

Kornblau added that of the 35 contributors mentioned in the Intercept story, 24 have not appeared on “Hardball” in the past year.

Last spring, when Kathleen Matthews announced her candidacy, the network and her husband said they had worked out ground rules to keep him at arm’s length from the primary. Kathleen Matthews, in her own email Wednesday, said her husband has had no role in fundraising.

“I’ve worked very hard to raise campaign funds from more than 8,000 individual donations over the past nine months,” she said. “Voters know that women can have separate careers from their spouses, and it’s offensive to me as a working woman and to these women senators and members of Congress to suggest they can’t get onto ‘Hardball’ on their own merits.”

The 8th District race is proving to be one of the most expensive primary contests in the nation, reflecting both the wealth of the district and the access of some candidates to deep pockets — his own, in Trone’s case, and nationally known politicians and celebrities in the case of Matthews.

The contributions cited by the Intercept include Sens. Kirsten Gillibrand (N.Y.), Claire McCaskill (Mo.), Barbara Boxer (Calif.) and Edward J. Markey (Mass.), former senator Tom Daschle (S.D.), and former congressman Martin Frost (Tex.), all of whom are Democrats. A small handful of the donations came shortly before or shortly after “Hardball” appearances. A $10,000 contribution from Off the Sidelines, Gillibrand’s PAC, came on June 2, two days before she was a guest.

The contributions illustrate Kathleen Matthews’s place in a monied Washington ecosystem that includes figures from every White House administration from Jimmy Carter through President Obama. Many of the donors are friends or Chevy Chase neighbors of the Matthewses whose kids attended the same schools and who frequent one another’s charitable events.

An analysis this week by the Center for Responsive Politics called Kathleen Matthews “the pick of the Democratic establishment” and said she had more donors who were former members of the House or Senate than any of her rivals.

A study of her contributions through the end of last year found that nearly three-quarters of the money comes from outside Maryland.

Barve, a 25-year state lawmaker, said voters will have to decide “whether they support candidates who have represented their communities for decades or wealthy outsiders running for public office for the first time.”

Shudofsky, the Republican who called on MSNBC to suspend Chris Matthews, has his own Washington affiliations. He’s a consultant to CRTV, or Conservative Review TV, a political media company that produces a podcast hosted by radio commentator and constitutional conservative Mark Levin. Shudofsky said he does political analysis and research for the site but does not work with Levin.

Trone is a leading fundraiser for the Democratic National Committee and has hosted events for Obama, among others. He also employs lobbyists in state capitals across the country to pursue legislative and regulatory changes to help his national chain of big-box stores.

Another Democratic hopeful, state Sen. Jamie B. Raskin (D-Montgomery), declined to comment on the Intercept report.

(Roll Call Editor in Chief Melinda Henneberger, the wife of this story’s author, has been a “Hardball” guest but is not a Matthews donor.)