A left-leaning veterans group gave Rep. Joe Sestak (D-Pa.) his first endorsement Monday in his nascent primary bid against Sen. Arlen Specter (D-Pa.).

VoteVets.org endorsed Sestak, who officially announced last week that he would challenge Specter in the 2010 Democratic primary. The group, which bills itself as the “largest progressive group of veterans— also endorsed the three-star Navy admiral in his first run for Congress in 2006.

“Joe Sestak will bring the same honesty, integrity, and hard work with which he’s always served America to the U.S. Senate,— said VoteVets.org Chairman Jon Soltz. “Joe Sestak understands the unique challenges facing America — especially those of us who served and are serving — and stands firm on his principles. You always know where Joe Sestak stands.—

VoteVets.org PAC also announced that they will immediately donate to Sestak’s campaign.