Angela Alsobrooks projected to win Maryland's Democratic primary for US Senate: AP

Prince George's County Executive Angela Alsobrooks defeated primary opponent Rep. David Trone on Tuesday night, in the Democratic primary for Sen. Ben Cardin's open Senate seat.

Alsobrooks won with 52.6 percent of the vote, according to the Associated Press, in a tight primary that was still considered a toss up between the candidates heading into election night. The close race comes despite Alsobrook's endorsement from current senators, such as Democratic Connecticut Sen. Chris Murphy.

The Senate hopeful also saw an uptick in support from other members of Congress in March, after Trone used a racial slur during a congressional hearing. He later apologized and claimed he had misspoken.

The winner is expected to face former Maryland Gov. Larry Hogan in November, who leads both candidates in theoretical mash-ups. A former two-term governor of the state, Hogan's candidacy has made the race more competitive than typically expected in a liberal state like Maryland.