Reps. Donna F. Edwards and Chris Van Hollen went head-to-head for the first time Sunday in their quest to succeed retiring Sen. Barbara A. Mikulski (D), clashing on trade and Social Security at a campaign forum in Rockville.

Both Democrats promised to fight for abortion rights, equal pay and Social Security expansion at the event hosted by the Maryland branch of the National Organization for Women.

While Edwards emphasized her history as an activist and her experience as an African American woman, Van Hollen played up his leadership role in Congress and political effectiveness.

“A voice . . . at the table that’s a voice of a mom, that is the voice of a woman, when it comes to child care and equal pay is really important; when it comes to abortion, the voice at the table of a woman is different and important,” Edwards said.

Van Hollen countered that being a straight, white man had not stopped him from standing up for the marginalized in the House of Representatives or the Maryland State House. He fought discrimination against gay workers in the state legislature, he said, despite not being gay. He supported abortion rights against a female state senator who did not. And he helped pass a law creating savings accounts for children with disabilities despite having no one in his family with severe disabilities.

“These are human rights issues of equity that everybody should be invested in equally,” Van Hollen said.

Gender and race were not the only divisions between the two. Edwards hit her rival on retirement programs, saying that “when it was time to cut a deal, Mr. Van Hollen was willing to consider — those are his own words — cuts to Social Security and Medicare.”

She also noted that he recently endorsed a bill that would expand Social Security benefits, which she also supports. “I’m sorry to say that Mr. Van Hollen has not been there, and I’m glad to say that he’s right there right now,” she said.

Van Hollen pushed back, saying he led the effort to persuade President Obama not to cut Social Security by using a less-generous cost-of-living formula.

On trade, likewise, Edwards said that there were “differences in our records.” While both oppose an Asia trade agreement currently under negotiation, Edwards has consistently opposed free-trade agreements; Van Hollen has not. He said he looks at each trade deal individually before deciding whether it will help or hurt U.S. workers.

Van Hollen emphasized his role as chairman and then ranking Democrat of the House Budget Committee, saying he wrote a spending plan designed to help low-income women and men, and was working with Minority Leader Nancy Pelosi (D-Calif.) to fight for Democratic priorities in the GOP-controlled House. He suggested that his rival was less electable than he was, warning that the general election in this blue state will not be a cakewalk.

“This is going to be a tough battle,” he said, pointing to last year’s election of Gov. Larry Hogan (R) over his Democratic opponent. Van Hollen touted endorsements from officials across the state, particularly his support from women and black leaders. Yvette Lewis, the most recent former chair of the state Democratic party, announced Sunday that she would co-chair Van Hollen’s campaign.

Edwards, a community activist before taking office, painted herself as more of an outsider. Although Van Hollen said he fought President George W. Bush’s attempt to privatize Social Security in Congress, Edwards — who was not elected until 2008 — said that the outside pressure campaigns she was involved in had at least as much impact. On abortion, she said, there was “not a dime’s worth of difference” between her and Van Hollen. But “I started working on these issues long before I started working in Congress,” she said.

She also disputed the implication that she was ineffective: “I’ve proven that I can get things done.” She pointed to an early victory: an after-school dinner program for students receiving free or reduced-price lunch. She helped with NASA reauthorization, she said, and fought for union jobs.

At the same time, Edwards acknowledged that she has less power in Congress than Van Hollen, calling herself “a junior member of the House of Representatives.”

Both described recent unrest in Baltimore as a sign that inequality must be addressed. Van Hollen opened by noting that he was in Baltimore on Saturday and again Sunday. Edwards wrote an op-ed for The Washington Post reflecting on tension with police, from the perspective of a black mother.

On that issue, though, most eyes have been on Rep. Elijah E. Cummings (D), who lives in and represents the area at the center of protests. Cummings, who initially said he was exploring a Senate bid, told reporters last week he is too busy trying to keep the streets calm to think about the 2016 race.