PROVO — Nearly 40 percent of registered Republican voters in Utah's 3rd Congressional District are undecided with Tuesday's primary between incumbent Chris Cannon and challenger John Jacob just days away.

Cannon is running television ads and both candidates are scrambling to line up influential endorsements even though it is unlikely they can change the minds of most voters or effectively craft messages to the undecided voters, consultants with both campaigns said while discussing their strategies Wednesday during a Public Relations Society of America luncheon in Provo.

"Our polls show that 38 percent haven't decided who to vote for," Jacob press secretary Hayden Hill said after the lunch.

Cannon campaign manager Nathan Rathbun confirmed during the event that a large bloc of voters are undecided, but he and Hill agreed the Cannon-Jacob race would boil down to how well the two campaigns do at getting voters who have chosen their candidates to go to the polls on Tuesday.

"This election will be won or lost based on who does better getting their voters out to vote," Rathbun said.

The turnout for the early summer primary is expected to be low, between 13 percent and 18 percent. For Jacob, the lower the better, with the hope that Cannon supporters would stay home while Jacob backers, energized by his challenge, would then cast enough ballots to push the election his way.

Cannon launched his television ad campaign Sunday night with commercials on three Salt Lake City stations. The spots have run on local cable during breaks on Fox News Network and CNN.

Cannon also has a new radio spot that slams national immigration reform groups for "their vicious smear campaign" against him. Those groups, mainly Team America, which is running a radio ad ridiculing Cannon for saying he is tough on illegal immigration, want Cannon replaced by Jacob, who they believe is stronger on the issue.

Jacob and others have tied Cannon to a Senate bill that creates a path to citizenship for illegal immigrants. They have complained that it is similar to a bill Cannon backed two years ago.

Rathbun said Wednesday that Cannon is against any path to citizenship for illegal immigrants. Instead, Cannon supports legislation that would create a guest-worker program that would allow some illegal immigrants to remain in the country for up to three years. The program would be extendable but would not provide an opportunity for citizenship, Rathbun said.

Jacob and others have called that an amnesty. Cannon has said it is not because it does not allow for citizenship and would likely require those who qualified to return to their native country at some point in the process.

In a week where Cannon has received endorsements from President Bush and first lady Laura Bush, he released a new one Wednesday from one of the toughest critics of the Senate bill and its path-to-citizenship proposal, House Judiciary Committee chairman James Sensenbrenner, R-Wis.

In a recorded message, Sensenbrenner said Cannon is "a major force in Congress."

"And long before it was fashionable, Chris Cannon was working with me to stop illegal immigration. Just about everybody in Congress is talking about immigration, but Chris Cannon is one of the few doing the heavy lifting to actually solve the problem."

Cannon also was endorsed Wednesday during a press conference in Salt Lake City by seven Utah state senators, 18 state representatives and 16 mayors in the district, including the mayors of Provo, West Valley City, Herriman and Orem.

Jacob has taken a hard line on illegal immigration. He is against any amnesty and any guest-worker program, Hill said.

Meanwhile, Jacob has an endorsement from the Vietnamese for Fair Immigration.

"Since 80 percent of illegal aliens are from Latin America, amnesty for illegal aliens is preferential treatment for Latino immigrants and discriminates against non-Latino immigrants. In short, amnesty is racism," VFI director Hoan Hoang said in a statement. "John Jacobs opposes this racism; it is why we endorse John Jacob for Congress."

"I appreciate the sincere support of this worthy group and echo their sentiments that the immigration problem has many facets that are often overlooked," Jacob said. "Amnesty is not the answer. It disregards the rule of law and unfairly rewards people for breaking the law by entering our country illegally."

Rathbun and Hill said they have carefully crafted their campaigns to target Republicans with a propensity for voting in primaries.

Hill said the negative Team America radio ads, which include a laugh track after each claim by Cannon that he is tough on illegal immigration, have been one of the three largest issues she's had to address.

"We support Team America and agree with some of their policies," Hill said. "They're our friends. But by law we can't talk to them or coordinate anything. And some outside groups don't understand the nuances of Utah campaigning."

The main nuance is that "Utah hates negative campaigning," she told the public relations professionals. "Utahns won't tolerate it. If you go negative, they won't like you. They want you to be their friend. They want to like you and to think you'd be a great neighbor."

Hill tried to inoculate Jacob against backlash from a Team America-style ad. Jacob's first radio spot, which continues to run, has him explaining that he won't go negative and that if an ad doesn't include a statement from him that he approved it, he had nothing to do with it.

Cannon was in Washington, D.C., on Wednesday. The House Resource Committee approved a bill Cannon introduced in May 2005 to trade scenic, state-owned land in Grand and Uintah counties for less sensitive land owned by the Bureau of Land Management.

Revenue generated from the state land will go to public education in Utah.