Sen. Ken Salazar Facing Potential Primary Challenge?

Sen. Ken Salazar's probable 2010 campaign has enemies--from within the party.

One of the more principled and less vitriolic statements on Salazar's record at SquareState (debating whether Salazar is "liberal or conservative"):

I won't vote for Salazar at any stage in the 2010 elections. He might not have principles, but I do. Democrats' acceptance of Salazar's voting habits is putting the party before everything else.

That sounds familiar . . .

Will the Democrats actually manage to stage a primary battle against the incumbent, mounting a Netroots-style insurgency? Or will this simply be progressive overreach, as party hard-liners reject Salazar's "centrist" appeal for a more palatable candidate (to Dems and progressives) as a result of what they perceive as Colorado's shift from red to blue?

**Update--civil war in the lefty blogosphere erupts over Salazar