JUDY WOODRUFF: Now: in a volatile election year, an unexpected competitive Democratic primary race in Arkansas.
And to "NewsHour" correspondent Spencer Michels.
SPENCER MICHELS: U.S. Senator Blanche Lincoln seemed right at home at a Farm Bureau candidates event in rural Craighead County in Northeast Arkansas.
This is rice and soybean country, where people take time out for a good crawfish feed and tailgating party. Here, farm policy trumps almost anything else when it comes to politics. Lincoln's position as chairman of the Senate Agriculture Committee would normally put her in good stead with her constituents.
TERRY HALL, farmer: She's getting a lot of fire from even the farming industry right now, but she -- I believe she's going to help the farmers.
SPENCER MICHELS: But, this year, Lincoln is fighting for her political life. She's one of the only Democratic incumbent senators facing a serious challenge in the primary election.
Lincoln campaigned with her sister and her mother by her side, fielding voters' questions. One woman thought the senator was swaying too far to the right.
WOMAN: But I'm going to vote for you anyway.
SEN. BLANCHE LINCOLN, D-Ark.: I appreciate it. We need you. We definitely need you.
SPENCER MICHELS: Others were concerned she's gone too far to the left, because, after being a holdout, she voted for health care reform.
CORA JEAN LILES, Arkansas: I think, as a citizen, you have failed the people of United States.
I'm not going to vote for her now, no. And I know, all my friends, they say, she must go.
SPENCER MICHELS: It's a fine line Lincoln is trying to walk. A conservative Democrat in her second term, Lincoln is fighting for reelection to a Senate seat that's been in Democratic hands since Reconstruction.
That may be a tough trick to pull off, according to Arkansas Times columnist John Brummett.
JOHN BRUMMETT, columnist, Arkansas Times: Blanche Lincoln's problem is that she's catching it from all sides, because the conservatives blame her for voting for the health care bill; the liberals blame her for having insisted on taking the public option out.
SPENCER MICHELS: Lincoln's seat is one of several that are crucial to the Democrats trying to keep control of the Senate.
Hal Bass, dean of social science at Ouachita Baptist University thinks moderates like Lincoln are facing a special challenge this year.
HAL BASS, dean of social science, Ouachita Baptist University: I think, when you find yourself positioned in the middle in a polarized political environment, like we have right now on the national scene, you are both vulnerable and valuable.
You are valuable in the sense that you are in a position to influence outcomes in an extraordinary fashion. But you are vulnerable because extremists, if you will, on both sides of the spectrum are going to find much to dislike in your performance.
SPENCER MICHELS: Is there a place for a moderate in today's political scene?
SEN. BLANCHE LINCOLN: I think so. And I hope so, for the sake of the country. I think that's where most Americans are. I think most Americans want us to get results. And I think they understand that you get results by -- by finding common ground.
SPENCER MICHELS: Even though Lincoln has often disagreed with the administration, she is still vulnerable because anger at Washington, D.C., and at President Obama is high in Arkansas. She spends much of her time on the stump and in her ads distancing herself from the president's agenda.
SEN. BLANCHE LINCOLN: I voted against giving more money to Wall Street, against the auto company bailouts, and against the cap-and-trade bill that would have raised energy costs on Arkansans. Some in my party didn't like it very much, but I approve this message because I don't answer to my party. I answer to Arkansas.
SPENCER MICHELS: Lincoln's immediate test is to win the Democratic primary election, where she is being attacked primarily from the left.
Her main rival is Bill Halter, the lieutenant governor, a former Rhodes Scholar who served as a budget and Social Security official in the Clinton administration, and who claims Lincoln is not a true Democrat.
LT. GOV. BILL HALTER, D-Ark., senatorial candidate: Listen, fellows, I'm running for Senate, and would -- would love your vote.
SPENCER MICHELS: Halter says he would reduce the influence of big money in Washington, oppose tax reductions in order to fight the deficit, and support a public option in health care reform.
Polls say Halter is trailing Lincoln by about 8 percent, but he's pushing hard.
ANTHONY FALKOWSKI, Arkansas: This entire political race is up -- it's just up for grabs. I like something about Bill. I like his freshness, his entrepreneurial spirit. And Blanche is somewhat tested.
SPENCER MICHELS: Halter has received financial support from labor unions that abandoned Lincoln after she opposed bills that would make it easier to organize workers. Union groups have paid for several anti-Lincoln TV commercials.
NARRATOR: Middle-class jobs are disappearing, thanks to Washington politicians like Blanche Lincoln. For 15 years, Lincoln supported bad trade deals, killing jobs in Arkansas. Lincoln took millions from Washington special interests. She listens to them, not us.
SPENCER MICHELS: Brummett says the race is unique in state history.
JOHN BRUMMETT: You have got Bill Halter coaxed into the race and funded in the race and energized by national labor unions, MoveOn.org, raising his money that way, doing so in a way that, in a normal circumstance, would go against all the truths we know about Arkansas politics, which is that we are a nominally Democratic culture, but only because our candidates here separate themselves from the national Democratic Party. This is a state that has gotten redder by the minute.
SPENCER MICHELS: For that reason, Bill Halter, regarded as the liberal in the race, rejects that label.
LT. GOV. BILL HALTER: I have a lot of positions that people would regard as conservative. Some would regard them as middle-of-the-road, and then other positions progressive.
But, to your question of why take on an incumbent senator, the reason is that Washington is not working for middle-class Arkansas families. People are -- are tired of all the money in politics.
NARRATOR: Blanche takes care of Wall Street.
SPENCER MICHELS: Early in the race, Halter had attacked Lincoln as a tool of Wall Street. But Lincoln introduced a strict financial reform bill this month, a bill Republicans and Wall Street don't like, a move she may have made because of Halter, says Brummett.
JOHN BRUMMETT: A major national issue has been influenced by what's going on in Arkansas politics, because, absent this -- this opposition from the left, Blanche Lincoln wouldn't have, I don't believe, come out with this derivatives bill that's tougher even than the White House wanted, tougher even than the -- than Senate liberals had proposed.
SPENCER MICHELS: So, Bill Halter is pushing her to the left?
JOHN BRUMMETT: Yes, he's pushing her to the left.
SPENCER MICHELS: Lincoln says, that's absurd.
But you weren't that tough on Wall Street earlier. And now you have gotten tougher on Wall Street all of a sudden.
SEN. BLANCHE LINCOLN: Well, now, I have the responsibility, as chairman of that committee, to produce a bill that, yes, is going to get the job done. Before October, I didn't have that responsibility.
SPENCER MICHELS: And it's not because Bill Halter is pushing you in that direction?
SEN. BLANCHE LINCOLN: Oh, heavens no.
SPENCER MICHELS: In some ways, this race reflects more about the state of the nation than the state of Arkansas.
While Republican John McCain won Arkansas by 20 points in 2008, this state elects plenty of Democrats, including, Bill Clinton, of course, and the current two U.S. senators. So, who it elects this time to the Senate, a liberal, a conservative Democrat, or a Republican, could well reflect the mood of the electorate beyond the Arkansas River.
Emotions are running high in the race. Supporters of each candidate tried to grab attention before a recent televised debate in Little Rock between Halter, Lincoln, and the third Democratic candidate, conservative businessman D.C. Morrison. Morrison paints himself as anti-Washington and anti-liberal. He says he's a Democrat by birth.
D.C. MORRISON, D, Arkansas Senatorial candidate: I'm not happy with either political party. I'm an American first, an Arkansan. I'm a member of several hunting clubs. I'm a Christian. I'm a father. And then, way down the list, I'm a Democrat.
SPENCER MICHELS: Morrison could get enough votes -- polls show about 10 percent -- to force a runoff in the primary between Lincoln and Halter. Polls indicate either Lincoln or Halter will have a tough race against whoever is the Republican nominee this fall. Eight Republicans are vying for their party's nomination on May 18.