WASHINGTON — The leading Democratic candidates to replace Sen. Barbara A. Mikulski went on the attack Friday during the first debates of the high-profile contest, criticizing each other's records as they made vastly different pitches to Maryland voters.

Reps. Donna F. Edwards and Chris Van Hollen, longtime colleagues from neighboring districts who are now locked in one of the nation's most competitive Democratic primaries, engaged in a feisty, hourlong exchange on WAMU-FM, sparring over trade, Social Security and criminal justice. The candidates met again hours later at a forum in Greenbelt.

Van Hollen, a Montgomery County Democrat who was trailing Edwards in a Baltimore Sun/University of Baltimore poll last week, was at his most aggressive yet in pushing back on her criticism and opening new lines of attack.

The Montgomery County lawmaker criticized Edwards repeatedly for what he said was poor constituent services, and he argued she wasn't talking about her record because it is less than substantial.

“Ms. Edwards, in this race, is not running on her record,” the Montgomery County Democrat said on the “Kojo Nnamdi Show.”

“A lot of rhetoric, but no results.”

Edwards, for her part, opened a new line of criticism against Van Hollen, saying that he favored truth-in-sentencing when he was a state lawmaker in Annapolis.

Criminal justice has carried particular salience this election year as many Democrats — including Hillary Clinton, the front-runner for the presidential nomination — have been pressed on prior tough-on-crime positions that are now out of sync with the thinking in both major parties.

“It is because of legislators like him that we've seen increased incarceration rates in Maryland and across the country,” Edwards said. “I've been leading the charge for reform.”

The Prince George's County lawmaker was apparently referring to a bill Van Hollen drafted as a state senator in 2002 that would have limited a judge's ability to reduce a sentence post-conviction, requiring the judge to wait a year before doing so in cases of violent crime.

The effort, proposed by several Democratic and Republican lawmakers, was ultimately put down by legislative leaders, according to reports at the time.

More broadly, the debate reflected arguments the two lawmakers have made since Mikulski announced last March she would not seek a sixth term.

Van Hollen returned repeatedly to a central theme of his campaign: his self-described ability to work with others to advance an agenda. Edwards has framed that experience as a detriment, arguing that Van Hollen is part of the establishment and has sacrificed liberal principles to make deals.

“Unlike Mr. Van Hollen, I was not willing to trade away the hard-earned benefit of Social Security just to cut a deal,” Edwards said. “I think the American people and Marylanders are tired of career politicians willing to trade away our principles.”

Van Hollen fired back by noting Edwards' 2001 vote against a controversial fiscal package that raised the nation's debt ceiling.

“Ms. Edwards has not been telling Maryland voters the truth,” Van Hollen said. “Ms. Edwards joined the tea party to allow us to default on our debts. She voted with the tea party; I voted with Senator Mikulski.”

In one particularly poignant exchange, the candidates debated the significance of the many endorsements Van Hollen has secured. Edwards has received backing from some elected officials and unions, but Van Hollen has locked up endorsements from the best-known of them.

“It is no surprise to me that the political establishment has endorsed the political establishment,” Edwards said. “Endorsements don't win elections.”

Polling in the race has varied widely, with a series of surveys in recent months finding the contest a dead heat. This month, the Sun/UB poll found Edwards with a 10-point lead.

Van Hollen had raised significantly more money by the end of last year to build a better than 10-to-1 cash advantage over Edwards.

But two factors have potentially undermined that advantage. Edwards has likely benefited from polls showing a close race. And an outside super PAC associated with Washington-based Emily's List, which helps elect Democratic women who support abortion rights, has spent more than $1.4 million on advertising in the Baltimore media market on her behalf.

Edwards, who has represented the 4th Congressional District since 2008, and Van Hollen, who has held the 8th District since 2003, are both popular at home. That has left the Democrat-rich Baltimore region as the contest's main battleground.

A second candidate exchange Friday, organized by the Prince George's County Young Democrats and the Eleanor & Franklin Roosevelt Democratic Club, was lower-key, though the candidates spent more time discussing immigration, foreign policy and student debt.

The debates were the first in what is expected to be a series of shared stages for the candidates. The Baltimore Sun, WJZ-TV, the League of Women Voters and the University of Baltimore are sponsoring a debate next Friday. Maryland's primary is April 26.

Edwards, 57, has frequently spoken of the historic significance of her candidacy. Edwards would be the first African-American to represent Maryland in the chamber, and only the second black woman elected to the Senate.

Asked whether race matters, Edwards said it does in terms of bringing a different perspective to the overwhelmingly white Senate — a consideration in the contest, she said, but not a determining factor.

“I think in a state that is the home base of Harriet Tubman, that it's really important for us to recognize that there's some significant gaps in the United States Senate,” Edwards said. “I look forward to representing Marylanders, no matter where it is that they live.”

On that point, Van Hollen agreed.

“I'm fighting for every vote,” said Van Hollen, also 57.

“When I talk to people across the state, regardless of race, regardless of gender, what they're looking for is someone who can deliver results.”

john.fritze@baltsun.com

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