WASHINGTON An anti-incumbent mood in the United States threatens to claim another victim on Tuesday as voters in 11 states pick Democratic and Republican candidates to face off in November congressional elections.
Senator Blanche Lincoln, a moderate Democrat, is fighting for her political life in her Arkansas runoff race as she seeks a third term.
In California, primary votes also will determine whether Republicans will back two female former corporate CEOs for high office.
Senate Majority Leader Harry Reid, a Nevada Democrat, will find out if he will face a "Tea Party" Republican conservative in his uphill battle for re-election.
The headline vote will take place in Arkansas, where Lincoln, author of a key segment of the financial regulation bill being debated in Congress this week, is in a run-off election required after she won a May 18 primary vote but failed to win the necessary majority.
Polls suggested Lincoln is at risk of losing to the state's lieutenant governor, Bill Halter, in the race for the Democratic nomination to face Republican Representative John Boozman in the November 2 elections.
A victory by Halter, who has been backed by unions and liberal groups, would be a stinging defeat of the Democratic establishment, including President Barack Obama and former President Bill Clinton, who is from Arkansas and helped Lincoln get elected in 1998 and campaigned for her last week.
Lincoln has faced anger from the left for her opposition to parts of U.S. healthcare legislation -- she eventually voted for it -- and from conservative Democrats critical of her support for bank bailouts.
"People felt that she had grown a little bit detached," said Jennifer Duffy, a political analyst at the nonpartisan Cook Political Report.
A defeat of Lincoln would extend Obama's losing streak. In past months he has backed Democratic candidates in races in Pennsylvania, New Jersey, Virginia and Massachusetts and all have lost.
Lincoln could become the fifth incumbent to lose thus far in the election cycle. Many incumbents are having difficulties as they face recession-weary voters fed up with the economic record of both parties in Washington in recent years.
A Washington Post poll published on Tuesday found that only 26 percent of the public approved of the job Congress was doing and only 49 percent approved of the way their own U.S. representative was handling the job. The numbers were worse than in 1994, when Republicans recaptured control of the U.S. Congress for the first time in 40 years.
"Fundamentally, it's the economy," said University of Virginia political science professor Larry Sabato. "That's at the heart of most of the unrest."
Or, as Republican strategist Tucker Eskew put it: "If you look like a politician and you talk like a politician and you wear experience as your armor, you are vulnerable in 2010."
MONEY TALKS IN CALIFORNIA
In California, Republicans were deciding on their challenger to face incumbent Democratic Senator Barbara Boxer, who for the first time is facing an uncertain re-election bid.
Millionaire Carly Fiorina, the former chief executive of computer maker Hewlett-Packard Co., has built a double-digit lead in the polls over moderate Tom Campbell and conservative Chuck DeVore.
In the Republican race to replace Governor Arnold Schwarzenegger, billionaire and former eBay Inc CEO Meg Whitman leads state insurance commissioner Steve Poizner.
The winner will oppose presumptive Democratic nominee Jerry Brown, a former governor and long-time figure in state politics, in November.
California's race for governor is on track to be the most expensive campaign in U.S. history outside a presidential contest, with the two Republican candidates alone spending more than $100 million in the primary.
The Republicans in both races are battling over who is a true conservative candidate, a key issue in California where unemployment is at a modern record 12.6 percent and the state government has a $20 billion budget gap.
Nevada's Harry Reid, struggling to avoid being ensnared in the anti-incumbent fervor, would likely see a way to stave off defeat if Nevada Republicans choose Tea Party favorite Sharron Angle.
Angle is in a dead heat with establishment candidate Sue Lowden, a former head of the Nevada Republican Party.
South Carolina, which endured Mark Sanford, the Republican governor whose divorce was prompted by his affair with an Argentine mistress, is now the focus of new sexual accusations in the race to replace Sanford on Tuesday.
Republican state representative Nikki Haley, backed by conservative darling Sarah Palin, has faced allegations from two Republican operatives that she had engaged in adultery with both of them, charges she denies.
(Additional reporting by Peter Henderson; Editing by David Alexander and Bill Trott.)