Reps. Donna F. Edwards and Chris Van Hollen.

Rep. Chris Van Hollen (D-Md.) appears to have taken a small edge in the heated Senate primary race against fellow Rep. Donna F. Edwards (D-Md.), according to polling conducted by his campaign.

Van Hollen garnered 45 percent to Edwards’s 40 percent among likely Democratic primary voters, a margin that is not statistically significant but differs from recent independent polls that have showed the race to be nearly tied or favoring Edwards.

A Baltimore Sun-University of Baltimore poll released last month found Edwards with a six-point edge over Van Hollen overall, while a Gonzalez Research survey found Van Hollen up one point.

Both candidates are viewed positively in the newly released survey, which comes less than four weeks before the state’s April 26 primary. But Van Hollen again comes out slightly ahead, with a 60 percent positive rating to Edwards’s 53 percent. Van Hollen also leads in the key Baltimore media market, according to the poll, which includes both the city and surrounding suburbs.

Previous surveys have suggested that Edwards far outpaces Van Hollen in Baltimore City, while the congressman fares better in the rest of the region.

Van Hollen’s campaign openly questioned the results of the Sun poll, and the release of this survey is probably intended as to challenge the idea that Edwards leads the race. Private polls that are released publicly tend to be slanted toward their favored candidate’s campaign.

The tight race has drawn broad national attention, with a super PAC run by the Democratic women’s group Emily’s List spending millions on television ads touting Edwards’s campaign. Van Hollen has received his own super PAC support in recent days from the National Association of Realtors. He began airing ads in the expensive D.C. media market this week.

For the past two weeks, the candidates have been sparring regularly at debates and forums around the state, clashing over trade, campaign finance reform and other issues.

Van Hollen has stressed his years of experience and legislative accomplishments as a lawmaker in Annapolis and on Capitol Hill, while Edwards has talked about both her policy work and the perspective she would bring to the Senate as an African American woman who raised a son on her own and at times struggled economically.

The firm Garin-Hart-Yang conducted the poll for the Van Hollen campaign by surveying 604 likely Democratic primary voters on a mix of cellphones and landlines from March 28 to March 30, including 294 in the Baltimore area. The margin of sampling error was plus or minus 4.1 percentage points for overall results.

The campaign did not say how many cellphone users were included in the survey. In 2014, 36 percent of Maryland adults were wireless-only, according to a National Health Interview Survey. An additional 14 percent said all or almost all household calls are received on their cellphones.

The primary will decide the Democratic nominee for the seat held by retiring Sen. Barbara A. Mikulski. The winner will be heavily favored in the November general election.

Scott Clement contributed to this report.