Rep. Chris Cannon holds a good lead over fellow Republican John Jacob in the 3rd Congressional District as Tuesday's primary approaches, a new Deseret Morning News/KSL-TV poll shows.

But when pollster Dan Jones & Associates breaks out those most interested in the election and hard-core GOP voters, the race tightens consider- ably.

Jones polled 617 registered 3rd District voters from Monday to Thursday. Among all the voters, Cannon leads 46 percent to 33 percent.

Still, whether Cannon wins the chance for a sixth term or Jacob knocks him out of office Tuesday will largely depend on which man can get his supporters to the ballot box, said Jones.

"Cannon has less than 50 percent of the vote," the poll shows, said Jones. "But at least he does have strong support among the Republicans" in the survey — where Cannon leads 60-35 percent. And the race is in a closed Republican primary, open only in their case to GOP-registered voters.

A few of the internal numbers stand out for Jones, who has polled in Utah more than 30 years.

"Eighteen percent still haven't made up their minds — such a high number usually hurts the incumbent. Thirty-eight percent have an unfavorable opinion of Cannon — that's very high negatives. And 42 percent of the voters haven't even heard of Jacob — not good."

While nearly 60 percent of those polled said they planned to vote Tuesday, that's highly unlikely.

Jones and Salt Lake County Clerk Sherrie Swensen predict only 10 percent to 15 percent of voters will actually cast ballots, which would be a poor voter turnout.

Cannon still leads, 49-42 percent, among those who told Jones they have a high interest in the election and "definitely or probably" will vote in the closed Republican primary.

But when you take the voters who have a "high interest" in the race and drop in the poll's margin of error, statistically speaking, Jacob could pull the race out.

Jacob's hope is that those who don't have a favorable opinion of Cannon cast ballots.

Jones found that only 47 percent of those polled said they had a "very favorable" or "somewhat favorable" opinion of Cannon, who was first elected to the 3rd District in 1996. More than a third of his constituents don't like him.

Even after winning the state Republican convention in May and running radio ads for weeks, Jacob, a millionaire in water and land development, remains unknown to many, with 42 percent of those polled having "never heard of him." A fourth said they had heard of him but had no opinion of the first-time congressional candidate.