Democratic hypocrisy in Arkansas?

I've been following the upcoming democratic primary in Arkansas between incumbent Senator Blanche Lincoln and Bill Halter with curiosity. Blanche Lincoln is one of the senate's leading centrists and drew the ire of liberals when she refused to throw her support behind a healthcare reform bill that contained a public option, even she had previously campaigned in support of the measure. She further complicated her relationship with the democratic base by refusing to sign onto comprehensive climate change legislation. This led Bill Halter, the lieutenant governor of Arkansas, to challenge her in the primary from her left flank. Bill Halter has been hailed by the liberal blogosphere as a "true democrat" and they have thrown their support behind his campaign.

For the last few months, democratic strategists have mocked the self destructive Republican focus on ideological purity, citing the party switch of Arlen Specter and the electoral defeat of Dede Scozzafava as prime examples that this type of party building does not work. The GOP has been so focused on ideological purity of late that the ultra-conservative Club for Growth exists simply to run primary candidates against moderates even at the cost of the general election. Many have attributed this strategy of ideological purity to the catastrophic GOP losses in the last two election cycles.

So this brings us to my question; is it hypocritical of the democrats to conspire against Blanche Lincoln? I am not inclined to think it is for several reasons. First, Blanche Lincoln's favorability ratings in Arkansas have hovered around 20% for over a year now. No incumbent this unpopular has ever been reelected. Bill Halter would arguably improve the democrats' position in this race, rather than detract from it. Second, Blanche Lincoln is a complete sellout. It is one thing to be a moderate politician and vote with your conscience. It is another all together to change your stances on key issues after receiving campaign contributions from Aetna. This is why you'll never hear about anybody trying to primary Ben Nelson (D-NE). He is a conservative, so he votes conservatively. No contradiction there.