IF LINCOLN IS SWAYED BY PUBLIC OPINION…. There are about five members of the Senate Democratic caucus who are likely to be the biggest obstacles to health care reform. Near the top of the list is Sen. Blanche Lincoln (D), a center-right Democrat from a state that’s moved sharply to the right in recent years.

She’s up for re-election next year, and Republicans have painted a bull’s eye on her back. Lincoln’s vote on health care policy is likely to make a big difference — and she knows it.

What she may not know, however, is that while Arkansas has become more painfully conservative lately, it’s also a state where Democratic reform ideas remain popular. A new Research 2000 poll, commissioned by the Progressive Change Campaign Committee and Democracy for America, helps make this clear.

Yet another public opinion poll in a state with a conservative Democratic senator shows that the public option not only is widely popular among voters, but could become a potent issue in the upcoming congressional elections.

One day after releasing a Research 2000 survey of Indiana residents — in a study designed to get the attention of Democratic Sen. Evan Bayh — the Progressive Change Campaign Committee and Democracy for America is going public with the results from Arkansas, home state of Democratic Sen. Blanche Lincoln. The findings are equally persuasive.

Specifically, Arkansans support a public option, 56% to 37%. Among independents in the state, it’s even better, 57% to 32%. Moreover, if Lincoln sided with Republicans on a filibuster, 35% of Arkansas independents would be less likely to vote for her, while only 10% would be more likely. Among state Democrats, 49% would be less likely to vote for her, only 7% more likely.

It’s unclear if Lincoln will face a primary challenge, but if she backs the GOP’s filibuster and has to earn the Democratic nomination, 48% of Democrats would be less likely to support her in a primary.

Progressive Change Campaign Committee co-founder Stephanie Taylor concluded, “This polling shows that voting against the public option — or helping Republicans block a vote on health care altogether — would be career suicide for Blanche Lincoln. It would alienate large numbers of Democrats and Independents when she’s already facing an extremely tough re-election.”

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.