If there is one thing the debates among the presidential candidates have enlightened us about, it is that illegal immigration is the emotional sleeper issue of the 2008 race.

Rep. Tom Tancredo, R-Colo., is the only candidate running solely on stopping illegal immigration (his new ad says it fosters the risk of more terrorism). The other candidates are shying away from the topic as they would a case of influenza.

What to do about letting illegal immigrants have legal driver's licenses has already tripped up Democratic Sens. Hillary Rodham Clinton of New York (first she was for the idea but now she's against it) and Barack Obama of Illinois (he's for licenses but he goes up the mountain and down the mountain when he talks about it). Democrats know Americans are increasingly agitated about illegal immigrants but also are adamant that they need the votes of Hispanic citizens, especially in key states such as Florida and those in the West with large numbers of Hispanics.

Republicans are equally befuddled when they talk about what the nation should do about illegal immigration. They run from the idea of "amnesty" and helped to scuttle President Bush's plan for temporary worker status, claiming it was an ill-disguised endorsement of amnesty for undocumented immigrants. On the other hand, Republicans also don't want to further alienate the growing number of Hispanic voters, already angry at them for their anti-immigrant rhetoric.

Americans right now tell pollsters they are most concerned about the war in Iraq, health care and the economy. But in recent weeks the worry about illegal immigration has slightly edged out terrorism for fourth place.

Supporting or opposing driver's licenses for people in this country without the right papers has become the current code for wanting "them" either made legal or sent back home.

As New Mexico Gov. Bill Richardson succinctly noted in the last Democratic debate, the main argument for giving licenses to anyone who passes the state tests is safety.

Immigrants, illegal and legal, are going to drive no matter what laws the states pass. Forcing them to get licenses and insurance has demonstrably made our roads safer. The American Automobile Association says that one of every five fatal accidents involves a driver without a valid license; unlicensed drivers are 500 percent more likely to be involved in fatal crashes than licensed drivers.

The major arguments against giving driver's licenses to illegal immigrants are that driving is a privilege that should be reserved for citizens and legal residents, and that a license can be used as identification to board planes by a terrorist. (A national identity card could solve that problem.)

So far, there has not been a full-fledged debate among either the Democratic or the Republican presidential candidates about immigration that would get below the surface of emotion and myth and prejudice. And if the candidates have their way, such in-depth probing won't happen because they don't want to be pinned down and lose votes.

But the candidates should be equally wary of what could happen next year. In the absence of a thorough airing by candidates of what is at stake in the struggle to find answers to the problem of inadequate border security and what should be done for the long-established illegal immigrants already in America, misguided anger against illegal immigrants could boil over.

Discrimination, even against innocent children denied health care and good education, would spread. Blacks and Hispanics, already competing for jobs and status, could be pushed into open warfare, vying to out-anger the other. Solutions for dealing with illegal immigration, including rational benefits and penalties, could become even harder to find.

The rest of the world already knows America no longer has an open-door policy. Even Iraqis who have endangered their own lives and their families by helping us are denied entry. An election based on intolerance and prejudice and untruths would be further damning.

Congress fled from the illegal-immigration issue this session. Now the candidates are fleeing just as fast, demanding that we stop asking them to be specific about their beliefs on controversial aspects of immigration.

Nobody thought to ask George W. Bush in 2000 if he favored the idea of pre-emptive war. This year we have every right to demand specific, in-depth answers from all the candidates on what should be done about and to illegal immigrants.