Utah has emerged as an improbable battleground in the fight for the future of the GOP, as the party's veteran U.S. senator — with nary a whiff of personal or political scandal — has become one of the most threatened lawmakers up for re-election next year.

Sen. Bob Bennett is no Northeast liberal. Raised in Salt Lake City, he built a successful business, manufacturing day-planners, that made him wealthy. His grandfather was a president of the LDS Church. His father served four Senate terms, meaning one or the other has held the seat for the better part of 60 years.

Yet those very attributes — longevity, seniority — only compound the challenge facing Bennett who, like other Republicans across the country, faces attack within the party from those who find him insufficiently conservative.

As this month's elections showed, the 2010 campaign is shaping up as another driven by a deep, throbbing anger against the political establishment. President Barack Obama has been a prime target at rowdy town hall meetings and "tea party" protests, and Democrats certainly have much to fear, as they hold the majority in Congress. But the free-floating hostility may pose a danger to members of both parties.

"This is not a Democrat problem. It's not a Republican problem. It's an incumbent problem," said Cherilyn Eagar, one of three Republicans, so far, taking on Bennett. "It's on both sides of the aisle."

A national poll issued last week reflected that sentiment. Only about half of the registered voters interviewed, 52 percent, said they would like to see their representative re-elected next year, among the most negative findings in two decades of Pew Research surveys.

As Bennett seeks a fourth term, Eagar and others, boosted by the conservative Club for Growth, cite his extended time in Washington and criticize his willingness to work with Democrats on issues such as health-care reform and the Wall Street rescue approved amid last year's financial crisis.

"People are fed up with the way Washington has historically conducted its business: horse-trading and giving this to get that," said Tim Bridgewater, another Republican running.

The insurgency is not limited to Utah. In several states, Senate hopefuls on the right have taken on comparative moderates preferred by GOP insiders, who consider them more electable.

In California, former Hewlett-Packard executive Carly Fiorina, bidding to face Democratic Sen. Barbara Boxer next year, faces Irvine Assemblyman Chuck DeVore, who is rallying support from conservatives nationwide. In Florida, Gov. Charlie Crist is fighting a stiff primary challenge from former state House Speaker Marco Rubio.