Del. Ana Sol-Gutiérrez, a candidate in Maryland’s 8th Congressional District race, speaks during a forum with fellow contenders in Rockville. (Evelyn Hockstein/For The Washington Post)

There was an unusual twist to the 25th candidates forum for Maryland’s crowded 8th District congressional primary: The contenders were allowed to question one another directly.

Their Q&A on Sunday, which wound up an estimated 37 hours of sometimes heated debate and discussion, enabled each of the nine Democrats to get one last poke at an opponent before next Tuesday’s primary.

But it did little to tease out any substantive new differences among the hopefuls, some of whom have been running hard for nearly a year in what has become one of the country’s most expensive congressional primary contests.

Del. Ana Sol Gutiérrez zeroed in on fellow candidate Kathleen Matthews, challenging — with no apparent foundation — the former television news anchor’s support of abortion rights.

“We understand that you have not always been pro-choice, that you were pro-life for a long time,” said Gutiérrez (D-Montgomery). She acknowledged after the session, held at the Jewish Community Center of Greater Washington in Rockville, that she had nothing to support her “understanding.”

“I have always been pro-choice,” said Matthews, a former WJLA anchor who has received an endorsement and financial support from Emily’s List, a political organization that backs Democratic women who endorse abortion rights.

Matthews speculated that her service on the board of Catholic Charities might be the source of “some confusion” but said her involvement with that group was focused on programs that address poverty and homelessness.

Wine retailer David Trone initially misfired his query, asking contender Del. Kumar P. Barve (D-Montgomery) why he voted earlier this month for a bill to exempt nail salon workers from unemployment insurance. The problem was that Barve voted against the measure, sponsored by state Sen. John C. Astle (D-Anne Arundel). It passed the House of Delegates 106 to 28.

Trone’s intended target was state Sen. Jamie B. Raskin (D-Montgomery), who did vote in favor of the legislation to bar manicurists and pedicurists — mostly immigrant women of color — from unemployment benefits because they are considered independent contractors. It passed the Senate 43 to 1.

Raskin told Trone he needed to “go back and check” the details of the bill in order to explain why he voted for it.

In an interview Monday, Raskin said he voted for the bill because it was presented to Democrats as “a consensus product” and that he had heard no opposition from labor unions.

“I’m on the side of working people, and if there’s a problem with the bill we should fix it,” Raskin said.

Trone, in turn, got a question from former State Department official Joel Rubin, who asked how the beer, wine and spirits retailer can run as a reformer (taking no campaign contributions) when he has spent millions “hiring PACs and lobbyists” to benefit his business.

Trone said he has never hired a PAC, and his only goal in retaining lobbyists was to push for consumer improvements, such as sales of craft beer in states where he had stores.

Trone also pointed out that Rubin “has a nice PAC funding him,” referring to a super PAC formed by a Pittsburgh friend who has purchased advertising on Rubin’s behalf in the race.

Moderators Josh Kurtz (Center Maryland blog) and Bruce DePuyt (NewsChannel 8) did their best to sharpen up the few policy differences among the contenders.

On recent U.S. trade deals, such as the Trans-Pacific Partnership, there was some daylight. Trone, Matthews and nonprofit executive David Anderson support them. Gutierrez, Raskin, Rubin and former Obama White House aide Will Jawando said they lack sufficient labor and environmental protections. Barve said the costs and benefits are “kind of a wash” and called for more investment in training programs to offset job losses caused by such pacts.

And on the nuclear agreement with Iran, only Anderson said he opposed it.

In a discussion about Citizens United v. FEC, the Supreme Court decision that allows corporations and unions to open their treasuries for unlimited independent political expenditures, there was general agreement that winning the White House and changing the composition of the court was the best option to overturn the ruling.

Trone agreed with the calls for change, but he also used the moment to defend himself against what he described as hostility toward his business success and his decision to self-fund his campaign to the tune of more than $9 million.

“There’s three millionaires on this panel,” he said, referring to Raskin and Matthews. “Yup, I’m guilty as charged. So I started a business with nothing, created a successful business. I used to think that was a good thing in America, a really good thing. You sometimes hear that’s bad, or you’re a bad person because you created 5,000 jobs around the country.”

Anderson, who has been outspent by nearly all of his opponents in the race, asked the audience to look beyond the millions of dollars in advertising.

“I advise you to vote your conscience, not your calculator,” he said.