Utah Attorney General Mark Shurtleff (R) didn’t expect that he would be eyeing a possible primary challenge to a well-liked U.S. Senator six months ago.

But when Sen. Bob Bennett (Utah) became a key Republican voice in the passage of the $700 billion Wall Street bailout bill and the creation of the Troubled Asset Relief Program last October, Shurtleff said he began to believe it was time for a change.

This week’s uproar over the American International Group and its bailout funding has only pushed the three-term attorney general further down the road toward mounting a primary campaign against Bennett in 2010.

“I love my job as attorney general,— Shurtleff said Tuesday. “It’s really what happened last fall and what’s going on right now that’s got me thinking that I can make a difference [in the Senate]. … There seems to be a huge interest and grass-roots desire to see things change.—

Shurtleff said he expects to make a decision on challenging Bennett by the end of the month and possibly as soon as next week. He is already moving ahead with fundraising in Washington, D.C., and Utah, and he has conducted polling to find out how he would fare against the three-term Senator.

Utah Republican insiders agree that Shurtleff represents a serious threat to Bennett because of his high name identification and his proven ability to campaign and raise money statewide during his races for attorney general.

And Bennett may have also given some indication of how much trouble Shurtleff could present. After Shurtleff’s name had surfaced as a potential candidate, Bennett offered the attorney general the chance to be a co-chairman of his re-election campaign. Shurtleff, who said the offer came in January when he was in Washington for the inauguration festivities, turned the Senator down.

When asked about that offer, Bennett’s son and campaign manager, Jim Bennett, described the matter as “a personal conversation that frankly was supposed to remain personal.— He added that “it speaks to [Shurtleff’s] character— that he would bring up the conversation for political purposes.

Jim Bennett said Shurtleff “wasn’t the first person called [for the co-chairman job], nor was he called in a political setting.—

The younger Bennett added that the campaign had been gearing up for the 2010 campaign well before Shurtleff made his interest in the Senate known. Holding up the example of former six-term Rep. Chris Cannon’s (R) unexpected primary defeat in 2008, he said last cycle offered several lessons for Utah politicians.

“Incumbents can’t take anything for granted,— he said. “You need to hit the ground running and you need to start early.—

The campaign expects to show $500,000 in cash on hand at the first-quarter filing deadline, Jim Bennett said.

Utah Republican political consultant Jeff Hartley said Shurtleff probably wouldn’t be able to “out-conservative— Bennett in a primary when it comes to social issues.

Shurtleff has been criticized by some on the right for not being tough enough when it comes to immigration, and he also ruffled some feathers among conservatives for questioning the wording of a 2004 amendment to the state constitution that prohibited same-sex marriages.

Hartley said Shurtleff would probably gain the most traction if he ran on a strict anti-Washington message that ties Bennett to out-of-control federal spending.

Besides Shurtleff, former Juab County attorney David Leavitt (R) has expressed an interest in running against Bennett this cycle. Leavitt — who did not make it out of the state party convention in his bid against Cannon last cycle — is the brother of former Utah Gov. Mike Leavitt (R).

Also mentioned as a possible GOP Senate candidate is attorney Mike Lee.

Shurtleff said he isn’t concerned about other primary challengers entering the race against Bennett. Perhaps that’s because Utah employs a party convention format where a candidate can avoid a primary if he earns 60 percent of the delegate vote. That means the more anti-Bennett delegates there are at the May convention, the better the chances are that a strong challenger, like Shurtleff, could pick up those supporters and hold Bennett at less than 60 percent.

If that happens, Bennett would then have to face his opponent in a June primary, which would likely be an expensive (by Utah standards) and closely watched affair.