Former Maryland lieutenant governor Anthony Brown. (Astrid Riecken/For The Washington Post)

Former Maryland lieutenant governor Anthony Brown on Monday endorsed the Senate campaign of the congresswoman he hopes to replace in the House.

“From her fierce advocacy on domestic violence issues to defending women’s rights, Donna has been a champion for Maryland women and their families,” Brown said in a statement.

Brown is the first candidate in the Democratic primary for Maryland’s 4th congressional district, centered in Prince George’s County, to endorse Rep. Donna Edwards, who currently holds the seat. Edwards is in a close race against Rep. Chris Van Hollen, from neighboring Montgomery County, in the Democratic primary for the Senate seat being vacated by retiring Sen. Barbara A. Mikulski (D).

Edwards has a rocky relationship with some local politicians. Prince George’s County Executive Rushern Baker III and state senators Joanne C. Benson, Ulysses Currie and Victor R. Ramirez are among those backing Van Hollen.

“It’s become apparent that the people who know her best are not supporting her,” Baker said on a conference call last week organized by the Van Hollen campaign to criticize Edwards.

But polling in the Senate race confirms that Edwards remains popular with constituents, particularly those who plan to vote in the April 26 primary. A recent Washington Post-University of Maryland survey found her leading Van Hollen in Prince George’s County 77 percent to 18 percent.

Edwards has not endorsed a successor. In the primary, Brown’s chief rivals are former Prince George’s County state’s attorney Glenn Ivey and state Del. Joseline Pena-Melnyk.

Van Hollen, likewise, has not taken a side in the crowded and expensive Democratic primary for his House seat. However, the top candidates running are all supporting him in the Senate race.