A new Washington Post poll reveals that voters are split among racial lines when asked to choose between Reps. Donna Edwards and Chris Van Hollen ahead of the April 26 Maryland Democratic primary. (Ashleigh Joplin/The Washington Post)

Maryland’s Democratic Senate race remains very much up for grabs three weeks before the primary, with voters sharply divided along racial lines, according to a new poll from The Washington Post and the University of Maryland.

The rare open Senate seat, being vacated by Sen. Barbara A. Mikulski (D) after 30 years, has sparked a heated and expensive battle between Reps. Donna F. Edwards and Chris Van Hollen. Edwards is trying to appeal to voters by emphasizing her inspiring personal story as a black single mother with an activist history. Her rival has responded with a bunch of endorsements from public office­holders and a relentless focus on his legislative record.

Faced with that choice, African American and white voters appear deeply split. Among all likely Democratic primary voters, Edwards leads Van Hollen by a statistically insignificant 44 percent to 40 percent. But likely black voters favor Edwards by a nearly 3-to-1 ratio. More than twice as many white voters support Van Hollen as back Edwards.

While Edwards also leads among women, that split has racial underpinnings as well, according to the survey, which was conducted in partnership with U-Md.’s Center for American Politics and Citizenship. Van Hollen leads by 23 percentage points among white women. But that preference is quickly erased by Edwards’s 51-point lead with black women, many of whom seem drawn by her argument that she is best suited to understand their needs and fight for those needs in an overwhelmingly white, mostly male U.S. Senate.

“Women get short­changed a lot,” said Edwards supporter Jacqui Battle, 59, a black mother of two in Prince George’s County. “It means a lot that she’s where she is, at the level she is, in her career.”

Prince George’s County Executive Rushern L. Baker III (D) and several other black elected officials from Edwards’s home county have endorsed Van Hollen — an advantage he touts at every opportunity. But Edwards still leads in Prince George’s by 59 points. (Van Hollen is nearly as highly favored in his home of Montgomery County.)

And despite extensive television ad campaigns and scores of visits and appearances, neither candidate holds a clear advantage in the Baltimore area, encompassing both the largely African American city and the whiter surrounding suburbs.

Both Edwards and Van Hollen frequently invoke Mikulski, a revered figure both nationally and locally, and the first female Democrat elected to the Senate in her own right.

Edwards notes that she, too, would make history as Maryland’s first black senator and the second female black senator. Van Hollen argues that he, like Mikulski, is a constituent-oriented and savvy politician.

The Post and U-Md. poll finds both candidates are well liked among registered Democrats in the state, with 56 percent rating Van Hollen favorably and 64 percent saying the same of Edwards; fewer than 1 in 6 rate either negatively. Six in 10 Democrats see each candidate as honest and trustworthy.

But white voters see Van Hollen as more effective.

“It would be nice if [Van Hollen] was a black lady,” said Tony Jacobs, 39, a software engineer from Olney who said he was impressed by the congressman’s fast rise to leadership. “But he is a better politician, and that’s really what matters. . . . When race and gender is part of the conversation, then you’re having the wrong conversation, because you’re not talking about passing laws.”

Yet despite Van Hollen’s position as the ranking Democrat on the House Budget Committee and his legislative achievements on Capitol Hill and as a state lawmaker in Annapolis, he wins no overall advantage on effectiveness.

Sixty-three percent of Democratic registered voters say Van Hollen would be effective at getting things done as a senator, but 66 percent say the same of Edwards.

Democrats are more likely to say that Edwards cares about people like them than they are to say the same about Van Hollen. And by even wider margins, she is seen as better representing women and African Americans, an issue that also illustrates the stark racial divide. While 59 percent of white Democrats say Van Hollen would do a good job representing the needs and interests of African Americans, that drops to 46 percent among black voters.

“For 25 years when we’ve been doing these studies, there’s been a fair amount of skepticism among black voters about the ability of white Democrats to represent them as well as similarly situated black Democrats,” said Michael Dawson, director of the Center for the Study of Race, Politics, and Culture at the University of Chicago.

“The one thing that might help him, which I suspect would be extraordinarily unlikely,” Dawson said of Van Hollen, “would be an endorsement from the president.”

Asked which candidate they would trust more to ensure that women earn equal pay for equal work, Democrats choose Edwards by a 37-point margin.

Michelle Moore, a 33-year-old African American from Baltimore, has good impressions of both candidates from television commercials. But ads aired by the women’s Democratic group Emily’s List on behalf of Edwards have helped Moore feel a particular kinship with the congresswoman.

Moore was raised by her grandmother after her parents split. Today, her fiance is incarcerated, and she is helping to raise his two boys with their birth mother.

Edwards “can relate to a lot of what women go through and what we need just to be able to provide good environments for our children to grow up in,” said Moore, who works in medical billing. “If they don’t understand it, how can they relate to us?”

Fifty-five percent of registered Democrats in the Post and U-Md. poll say it is at least somewhat important for their party to nominate a black woman to run for U.S. Senate, a number that rises to 67 percent of black Democratic voters.

Even some Van Hollen voters say they recognize the pull of Edwards’s campaign.

“I have some serious inner conflict in voting for a white man instead of a black woman,” said Sarah Wolf, a white 24-year-old Maryland legislative staffer from Chevy Chase. But, she said, Edwards seems to lack the “relationship skills” necessary to be an impressive lawmaker.

Van Hollen, she said, pleased her in particular by working to help people with intellectual disabilities. “He has a reputation for getting things done,” Wolf said. “And in order to get things done, you have to have the meaningful relationships.”

Still, Edwards’s attacks on Van Hollen’s record have resonated with some voters. Jean Cushman, 66, said she supports Edwards because the congresswoman shares her “very progressive” ideology.

The former nonprofit executive described Van Hollen as “more of an establishment candidate” who she fears would be more likely to back free-trade deals, oppose recognition for a Palestinian state and support the fossil-fuel industry.

With others, Van Hollen’s criticism of Edwards’s constituent services and legislative record have struck a chord. Christine Barnes, a 78-year-old white retiree in Baltimore, questioned why Edwards recently closed her office in Anne Arundel County, something Van Hollen has noted in debates and forums.

“I think he has actually done something — sponsored legislation,” Barnes said. “She less so.”

Both candidates have a chance to win new supporters before the April 26 primary. One in 6 likely voters has no opinion yet, and while more than half of Democratic voters say they are following the contest, only 18 percent are keeping track very closely.

Edwards, who fares better with registered Democrats overall than with likely primary voters, must also worry about turning out her supporters. In the Post and U-Md. poll, 45 percent of Democrats who described themselves as likely to vote in the primary were black. But in the 2008 presidential primary, exit polling found African Americans made up 37 percent of Maryland’s Democratic electorate.

Republicans will also choose a nominee in this month’s primaries. But the candidates are not as high-profile as Edwards and Van Hollen, and registered Democrats outnumber registered Republicans in the state more than 2 to 1. That means that the GOP nominee will be considered an underdog in the general election.

According to the Post and U-Md. poll, relatively few likely Republican voters are paying attention to the race. About 6 in 10 likely voters have no preference among the major candidates, and the gaps between the vote shares for those candidates are for the most part not statistically significant.

Maryland House Minority Whip Kathy Szeliga (Baltimore County) takes 15 percent. Trade association executive Chrys Kefalas stands at 11 percent. Former Pentagon official Richard Douglas is at 9 percent and tire company owner Joseph Hooe at 3 percent.

The Post and U-Md. poll was conducted March 30-April 3 among a random sample of 1,503 residents of Maryland reached on land-line and cellular telephones. The margin of sampling error is plus or minus 4.5 percentage points among the sample of 741 registered Democrats, and 5.5 points among the sample of 539 likely Democratic primary voters and 7.5 points among the sample of 283 likely Republican primary voters.

Emily Guskin and Fenit Nirappil contributed to this report.

Earlier versions of this report incorrectly said that Sen. Barbara A. Mikulski was the first woman elected to the U.S. Senate in her own right. In fact, Mikulski was the first Democratic female senator elected in her own right. The article has been corrected.