Sen. Blanche Lincoln (D-Ark.), who is a crucial swing vote in the Senate’s ongoing health care debate, called out the big guns for her re-election effort on Thursday, releasing a fundraising appeal this morning from former President Bill Clinton.

Clinton’s letter for Lincoln comes just two weeks before the fourth quarter Federal Election Commission fundraising deadline. The fact that Lincoln –‘who already has over $4 million in her campaign warchest — has deployed the former president 11 months before the general election may be a sign of just vulnerable the Senator believes she is heading into 2010.

While the National Republican Senatorial Committee and the state GOP are working hard to paint Lincoln as too liberal for her state she’s also been blasted by some in her own party who believe she’s become a roadblock to President Barack Obama’s agenda. In his letter, Clinton acknowledged that the moderate Lincoln is treading a tough path in the Senate.