Former Pennsylvania Lt. Gov. Mark Singel (D) on Thursday dropped out of the special election to succeed the late Rep. John Murtha (D), according to a source familiar with the decision.

A voicemail message left for Singel was not immediately returned, but southwestern Pennsylvania sources and the Pittsburgh Post-Gazette have confirmed he has left the race and is backing Murtha’s district director, Mark Critz, to be the Democratic nominee. Critz announced Thursday morning that he has the backing of the Congressman’s widow, Joyce.

Singel’s departure leaves former state Treasurer Barbara Hafer and Critz as the leading Democrats in the race for the 12th district seat. A lesser-known Democrat who was also running, Westmoreland County Commissioner Tom Ceraso, has also decided to get out of the contest.

Local Democratic officials will meet on March 6th in Delmont, Pa., to recommend a candidate to state party leaders, who will pick the nominee to run in the May 18 special election. The special is being held the same day as the state’s regularly scheduled primaries, when candidates will also be seeking nominations to run for a full term in November.