House Republicans have resisted making illegal immigration a major campaign theme this year, aware that their presidential candidate is at odds with them on the issue and voters are more focused on the economy.

Many GOP members have previously questioned McCain for co-sponsoring legislation with Sen. Edward Kennedy (D-Mass.) that would have put millions of illegal immigrants on a path to citizenship.

“Republicans think immigration is the issue to seal the deal for them, but it hasn’t been that,” said Lynn Tramonte, policy director for America’s Voice, an organization that supports the so-called comprehensive immigration legislation that McCain helped draft.

Even McCain’s critics agree that the issue has faded.

“It’s clearly not as salient of an issue as people thought it would be a year ago,” said Mark Krikorian, executive director for the Center for Immigration Studies, a conservative think tank devoted to border security and enforcement.

Of the 30 most competitive races listed by The Associated Press on Sept. 14, only 13 candidates have a section of their website addressing immigration. Reflecting shifting Republican attention, most of the sites feature sections on energy, terrorism and the economy.

Several campaigns say the shift is a reflection of what voters want to see addressed.

“When we’re out campaigning and going door to door, the No. 1 issue is energy prices,” said Tom Dunn, a spokesman for the campaign of Republican Tim Bee, who has challenged Rep. Gabrielle Giffords (D) for Arizona’s 8th district seat — which shares a border with Mexico. Dunn said immigration remains high on the list, although it is also tied into economic issues.

“The issue right now that we’re dealing with is the economy,” said Matt Leffingwell, a campaign spokesman for Rep. Jon Porter (R-Nev.), who faces a tough reelection challenge from Democratic state Sen. Dina Titus.

But another reason for the shift is to avoid the perception of the party rank and file and those running for the first time openly questioning their presumed leader on such a visceral topic.

Downplaying illegal immigration on the campaign trail leaves House Republican incumbents and candidates in a tight spot. On one hand, they are trying to win over a smaller group of voters, and depending on where the district is, illegal immigration could be a hot topic. But if they are too vocal on the issue, they could be seen as challenging McCain, who was elected to the Senate by a much larger and less parochial group of voters but could be hurt in the presidential election by public clashes with his party.

McCain survived attacks from Rep. Tom Tancredo (R-Colo.), who sought the party’s presidential nomination with a platform that focused attention on illegal immigration. Tancredo challenged McCain during the Republican primary debates on the topic, but other than that, his campaign never gained any traction. Tancredo is not seeking another term in the House.

Further dissonance in messaging from Republicans, Tramonte said, could hurt McCain’s chances.

“It’s absolutely a handicap for him [McCain],” Tramonte said. “McCain did have strong support among Latinos in Arizona and around the country,” she said, adding that that may be jeopardized by harsh rhetoric by Republican candidates.