SALT LAKE CITY (AP) — An array of rivals at Utah's GOP convention Saturday are lining up against Sen. Bob Bennett — a potential first victim in a national effort by some conservatives to drive out officeholders they view as not conservative enough.

The state's 3,500 delegates will determine whether to give the 76-year-old Bennett the party's nod to run for a fourth term.

His seven Republican rivals contend he longer has the credentials to represent "ultraconservative" Utah.

It's a position being heard elsewhere in the country as some Republicans shun moderate candidates in favor of those backed by tea party activists, such as with Senate races in Arizona, Kentucky and New Hampshire.

In Florida, Gov. Charlie Crist decided to run for Senate as an independent rather than face an almost certain primary defeat at the hands of tea party favorite Marco Rubio, Florida's former state House speaker.

It's too late for Bennett to take a similar route as state law prohibits him from running as an independent once he's filed as a Republican.

Recent delegate surveys show Bennett in third place behind attorney Mike Lee, 38, and businessman Tim Bridgewater, 49, who say they're better suited to reign in government spending.

The opposition to Bennett is specific, and can't be chalked up to a general anti-incumbency fervor. Neither of Utah's two Republican congressmen are at risk of losing their seats, and Republican Gov. Gary Herbert doesn't have any serious challengers.

Bennett is under fire for voting to bail out Wall Street, co-sponsoring a bipartisan bill mandating health insurance coverage and for aggressively pursuing earmarks.

Some delegates, who tend to me more conservative than other Utah Republicans, also are upset he's still in office after initially promising to only serve two terms when he first ran for office in 1992.

Bennett's best hope for survival is to get more than 40 percent of the delegates' votes and force one of his opponents into a June 22 primary. To help accomplish that, he's enlisted the help of former presidential candidate Mitt Romney.

Romney ran the 2002 Winter Olympics here, is a Mormon like Bennett and most of the delegates and is wildly popular in Utah, where he won 90 percent of the presidential primary vote in 2008. Romney is scheduled to introduce Bennett before the senator makes a last-minute plea to convention delegates.

Democrats also are choosing their nominee Saturday, but in heavily Republican Utah, whoever wins the GOP nomination is virtually assured victory in November. A Democrat hasn't been elected to the Senate since 1970.

Bennett has spent recent weeks focusing on how his seniority in Washington, benefits Utah, saying he's the only one in the position to save the Ares rocket program and thousands of jobs. He's also chided his opponents for failing to provide details on how they would shrink the budget, noting his proposal to cut entitlement spending.

He says his record has been mischaracterized by the anti-tax Club for Growth, which has spent heavily against him this year without endorsing any of his opponents.

And Bennett rejects the notion that he's not conservative enough, saying he just doesn't excel at providing sound bites for cable talk shows that simplify complex issues. Indeed, Bennett is a policy wonk who often expounds for 15 minutes at a time to provide the historical background to a single question.

"That's one of my problems," Bennett acknowledged in an interview. "On the other hand, I do have people who come up and say 'Now I understand. Thank you for going into that detail, because all I get out of the other candidates are sound bites.' So while it may be one of my problems to be a little professorial, it's also one of my strengths that I understand the details of the problem."

Other GOP candidates will watch Saturday's results closely, looking to see if its an indicator of things to come.

In Arizona, Sen. John McCain is in a tough primary fight against former Rep. J.D. Hayworth, a conservative talk-radio host. In Kentucky, Rand Paul, the son of libertarian Rep. Ron Paul of Texas, is gaining momentum in his challenge against the GOP establishment's pick of Secretary of State Trey Grayson to replace retiring U.S. Sen. Jim Bunning.

In New Hampshire, former Attorney General Kelly Ayotte is battling three Republican challengers to fill the seat being vacated by Republican Judd Gregg.