The endorsement represents a significant boost for Mr. Lancman's campaign and was sought by both of his Democratic rivals: Assemblymember Grace Meng and City Council member Elizabeth Crowley.

The Working Families Party has proven adept at winning local races, but this race in eastern Queens will be some new territory for the labor-backed party, whose strength is in central Brooklyn and the west side of Manhattan. It is also worth noting that WFP endorsements can mean different things, and it is also unclear how much effort they will put into this Congressional race, considering that all three of the candidates are considered fairly progressive.

According to sources who attended the WFP endorsement meeting, Mr. Lancman talked up his efforts to boost the minimum wage and noted how he opposed Gov. Andrew Cuomo's efforts to let the millionaire's tax expire.