Rep. Stephen Lynch (D-Mass.) will announce his special election bid for Democratic Sen. John Kerry’s Massachusetts seat on Thursday, a person close to him has confirmed.

Lynch’s move is not a surprise. Last week, it looked like a near certainty that he would enter the race. His decision will pit him against Rep. Ed Markey, the only other Democrat who has announced his intention to run. Kerry, Senate Democrats’ campaign arm and several prominent Bay State Democrats are all backing Markey.