A new Research 2000 poll commissioned by Daily Kos shows that Blanche Lincoln is not only vulnerable to a general election loss, but extremely vulnerable to a potential primary challenge from Lt. Governor Bill Halter.

The poll, with a margin of error of 4%, shows Lincoln with a 41/50 favorable/unfavorable rating, as opposed to Halter, who has a 36/25 rating with high undecideds, meaning he has some room to build on. The potential Republican challengers for Lincoln are all unknown as well.

Lincoln leads those Republicans but the margin is close. She’s up 42-41 on Gilbert Baker, 44-39 on Curtis Coleman, 45-31 on Tom Cox and 46-30 on Kim Hedren. This is much better for Lincoln than that disastrous Rasmussen poll from today, which showed her trailing all four challengers and not above 41% in any matchup. However, she’s still under 50% against everyone.

Halter trails Baker (42-34) and Coleman (40-35) but leads Cox (36-32) and Hedren (36-31), with high undecideds in all of those races.

R2K also did the head-to-head matchups between Halter and Lincoln in a primary:

Lincoln 42
Halter 26

That’s a pretty decent baseline, given the name ID. More importantly, if Lincoln filibusters health care, watch the numbers change:

Lincoln 37
Halter 27

The public option is favored by Arkansas respondents in the poll, 53-41, similar to a new Thompson-Reuters poll showing majority support (near 60%) for the public option nationwide. In fact, the public option is more popular than the overall health care bill. Democratic primary voters in Arkansas favor a public option 84-10.

Markos comments:

Given that 84 percent of like Arkansas Democratic primary voters support the public option, one can see how this apostasy would negatively affect her primary chances. 42% for an incumbent in a primary that would be dominated by activist-type Democrats is brutal for Lincoln. 37%? If Halter runs, and Lincoln decides to follow through on her promises to fight against the Senate Democratic health care plan, then there’s no way she gets past the primary. It’s that simple [...]

This poll shows that Lincoln’s obstructionism, rather than bolster her standing in Arkansas, is actually hurting her more. She has slid against the opposition, losing aground with all groups — Democrats, Republicans, and Independents. Her clumsy bungling of the health care issue stands in stark contrast with her colleague, Sen. Mark Pryor, who remains in positive favorability territory, 48-38.

If Halter runs, we’ll have a barn burner of a primary, and a real opportunity for progressives to strike back against one of the biggest obstructionists in the Senate, not just on health care, but on practically every issue we care about. And given Lincoln’s poor general election numbers (well below the 50 percent danger marker for incumbents), we’d likely have a better chance of holding the seat with Halter, who would be more likely to consolidate Democratic support and get them to the polls, while remaining competitive among incumbent-adverse independents.

This could be a game-changer in Arkansas.