Julie Hirschfeld Davis

WASHINGTON -- The tricky politics of immigration, an issue once seen as a driving force of the 2008 election, have relegated it to a back but hot burner in the presidential campaign debate and paralyzed Congress on the topic.

The searing rhetoric from opponents who brand that idea as "amnesty" has made the topic virtually untouchable, according to strategists and lawmakers.

"Politicians from both parties are caught between Lou Dobbs voters and Latino voters. Presidential candidates will avoid this issue -- both of them -- and when they can't avoid it, they'll straddle," said Tamar Jacoby, president of ImmigrationWorks USA, a coalition pushing for an immigration overhaul. "It doesn't pay as an electoral issue."

The high-profile Dobbs is a CNN host who has used his early-evening show as a platform to protest illegal immigration.

McCain and Obama have spoken of their support during the campaign for an immigration overhaul, but neither has made the issue a major part of his presidential bid. Each has reason to tread carefully.

McCain's position is a sore point between him and the conservative GOP base. He is caught between shoring up those core constituents and drawing support from Hispanics.

"He's trying to appeal to one group of voters that hates the other," said Cecilia Munoz of the National Council of La Raza.

Republican pollster Tony Fabrizio said it does not pay for McCain or GOP congressional candidates to highlight their party's rift on the issue. Those candidates lag far behind McCain in national polls that ask voters whether they support a Republican or Democrat for Congress.

"Why focus on what divides us?" Fabrizio said.

McCain sometimes has sent conflicting messages on immigration.

He hedged when asked whether, as president, he would sign legislation he helped write to legalize undocumented immigrants and now says such action should only be taken after border security is strengthened. But he also publicly lamented the defeat of his measure, calling it "my failure, too."

For Obama, who is struggling to win over Latino voters, the predicament is less pronounced but no less puzzling. On immigration issues where he and McCain differ, Obama's views are out of synch with those of most voters, polls show.

Obama's support for giving driver licenses to illegal immigrants is a prime example; polls show that the public overwhelmingly opposes it. Obama also supports giving legal status to immigrants who were brought to the United States illegally as children and have completed two years of college or military service.

Democrats "do want to be out front on it, but they fear alienating those blue-collar, skeptical voters," Jacoby said.

Obama got a taste of that backlash recently. He drew heavy criticism in the blogosphere for suggesting that conservative cable TV hosts who routinely rail against illegal immigrants are partly to blame for an increase in hate crimes against Hispanic people.

"A certain segment has basically been feeding a kind of xenophobia," Obama said at a fundraiser in Palm Beach, Fla. "If you have people like Lou Dobbs and Rush Limbaugh ginning things up, it's not surprising that would happen."

The comment was a nod to a widespread feeling among Hispanic voters that bitter rhetoric against illegal immigrants is really veiled racism against U.S. citizens and legal residents who are Latino.

"The volatility of the issue discourages the national candidates from aggressively promoting the need for comprehensive immigration reform," said Rep. Howard Berman, D-Calif. "When they're asked, they respond, but I've come to the conclusion that this campaign will not likely be a useful educational tool for demonstrating the compelling need for reform."

Candidates are finding other less-risky ways to telegraph their sympathy for Hispanic voters.

McCain has a TV ad praising Hispanics' service in Vietnam and Iraq and saying some "love this country so much that they're willing to risk their lives in its service in order to accelerate their path to citizenship." Obama spoke Spanish in an ad aired in Puerto Rico that focused on economic concerns.

In Congress, Democratic leaders are skittish about immigration votes. Instead, they are holding House hearings -- but no votes -- on a measure written by one of their more-conservative members, Rep. Heath Shuler of North Carolina, to strengthen border security and crack down on employers who hire undocumented workers.

One Hispanic Democrat, Rep. Raul Grijalva of Arizona, said his leaders were being "spineless." Others argue that Republicans, who have made it a strategy to force politically painful immigration votes on unrelated bills, essentially have blackmailed Democrats into taking tougher stances on the issue.

In February, for example, Democrats joined Republicans to forbid illegal immigrants from getting an economic relief tax rebate.

More recently, Senate Democratic leaders were forced to pull provisions from an emergency Iraq spending bill that would have awarded work permits for immigrant farm and seasonal workers.

"Congressional Democrats are struggling to figure out whether they want to sound like Republicans-lite or whether they want to actually get out in front of the issue and lead," Munoz said.

Rep. Jeff Flake, R-Ariz., a supporter of a broad overhaul, said candidates in both parties face that dilemma.

"You have to ask yourself, 'Do I want to really get out front on an issue that isn't really going anywhere and my opponent can demagogue it and misrepresent my position?' " Flake said. "If you're going to go out on a limb on something, there has to be a payoff, and on this, there just isn't."