State Sen. Katherine Clark won a crowded special primary in Massachusetts’ 5th District on Tuesday night, defeating  four other Democrats and most likely becoming the sixth woman ever elected to Congress from the Bay State.

Clark received 30 percent of the vote, beating Middlesex County Sheriff Peter Koutoujian, who recieved 22 percent of the vote, with 83 percent of precincts reporting, according to the Associated Press.

Clark was one of five Democrats running in this contest to replace Sen. Edward J. Markey, the district’s longtime representative before he was elected to the Senate in a June special election. Clark led the pack for most of the contest and was largely considered to be the front-runner by local Democratic operatives.

Clark is nearly assured to be the next member of Congress in this heavily Democratic district located in the Boston suburbs. President Barack Obama carried the district with 65 percent in 2012.

She will face attorney Frank Addivinola, a Republican, in a special general election on Dec. 10.

Massachusetts’ 5th District is rated a Safe Democratic contest by Rothenberg Political Report/Roll Call.