America's rugged, porous southern border has come to symbolize a broken immigration system, spawning a political debate especially fraught with perils. Nowhere is that more evident than in the presidential primary races.

The highly charged immigration issues have tripped up veteran politicians such as Sen. Hillary Rodham Clinton, who recently appeared to waffle on whether to grant noncitizens driver's licenses, and Sen. John McCain, who's backed away from a long legislative history advocating a path to citizenship for the estimated 12 million to 15 million people who've slipped over the border or overstayed their visas.

Pundits dub the immigration issue "a minefield," "a new third rail," as well as a "megaissue" because of its complexity and the strong emotions it evokes. Even the language used – "undocumented worker" versus "illegal immigrant" – has become a potentially volatile touchstone.

While immigration still comes in behind the war in Iraq, the economy, and healthcare issues when voters are polled about their concerns, it now beats out terrorism.

"Even more important, it's the high-intensity issue on both sides, and in this [primary race], high-intensity minorities are more important than majorities," says John Zogby, president and CEO of Zogby International, a polling firm. "It's also the ultimate wedge issue, because it's a zero-sum game."

In general, the Democrats support shoring up the border, having tougher enforcement in the workplace, and creating a way for "undocumented workers" to earn citizenship. Their mantra is "comprehensive reform." For Republicans, it's "tough enforcement": All support more border security and tough workplace enforcement, and most are adamantly opposed to creating any kind of "amnesty" for "illegal aliens." The exception is Senator McCain. While he has backed off stands openly advocating a path to citizenship, he still says it's important to "recognize the importance of assimilation of our immigrant population," according to his website.

Fault lines for each party

Within those fairly clear stances, there are political fault lines for both parties. For Republicans, the biggest problem lies in alienating the fast-growing block of Hispanic voters. That presents a serious challenge not just to the candidates, but to the long-term prospects of the GOP, most political analysts say.

The reason is that more Hispanics are voting. In 1992, Hispanics made up 4 percent of voters in the presidential election, according to an analysis of the data by Mr. Zogby. In 1996, it was 5 percent; in 2000, 6 percent. By 2004, Latinos made up 8-1/2 percent of voters. And many of them are in swing states such as Arizona, Colorado, Nevada, and Florida that President Bush won – some just barely – in 2004.

"The Republicans are losing one of the great swing votes in American politics – Hispanics and Latinos," says Larry Sabato, a political analyst at the University of Virginia in Charlottesville. "They're taking great offense at the Tom Tancredos of the world."

The presidential platform of Representative Tancredo (R) of Colorado says, "I am 100 percent opposed to amnesty…. I will secure our borders so illegal aliens do not come and I will eliminate benefits and job prospects so they do not stay." He also routinely ties the broken immigration system to the terrorist threat.

For many Hispanic voters, such adamant opposition to illegal immigration translates into opposition to Latinos in general. That became clear to them in the spring of 2006: Many Republicans abandoned Mr. Bush's efforts at comprehensive reform, and the House instead passed a bill that made it a felony to be an illegal immigrant and a felony to help one. That prompted mass demonstrations by legal and illegal immigrants and played a key role in that fall's election, which gave control of Congress to the Democrats.

Page: 1 | 2