FACTBOX: Leading presidential candidates on immigration

(Reuters) - With just three weeks before Iowa kicks off the state-by-state battle to choose the Republican and Democratic candidates for the November 2008 presidential election, politicians are walking a careful line between appeasing anti-immigration sentiment and trying not to turn off a growing segment of Hispanic voters.

Following is a summary of the leading 2008 U.S. presidential candidates' positions on immigration reform.

DEMOCRATS:

New York Sen. Hillary Clinton

Supports a guest-worker program for immigrants if it does not undermine U.S. workers' wages and favors giving undocumented workers a way to become legal workers. Backed building a border wall. Urges development of an employer verification system and higher penalties for employers who exploit illegal immigrants.

Former North Carolina Sen. John Edwards

Urges doubling the number of Border Patrol agents, installing surveillance technology to police the border and increasing enforcement against employers who hire illegal immigrants. Supports allowing illegal immigrants to become U.S. citizens if they avoid a criminal record, pay a fine and learn English. Opposes a guest-worker program that does not include workplace safeguards.

Illinois Sen. Barack Obama

Backs additional personnel, infrastructure and technology to safeguard U.S. borders and ports. Urges reducing application fees and improving speed and accuracy of FBI background checks for immigrants. Supports a program in which illegal immigrants pay fines, learn English, do not violate the law and go to the end of the line to become citizens. Favors creating a program for employers to verify an applicant's immigration status.

REPUBLICANS:

Former New York Mayor Rudy Giuliani

Supports building the border fence and maintaining 20,000 Border Patrol agents. Urges issuing a single biometric identification card to foreigners, creating a national database and removing those immigrants who have overstayed their visas. Backs deporting illegal immigrants who commit felonies and requiring immigrants to read, write and speak English. Opposes driver's licenses or similar identification for illegal immigrants.

Former Arkansas Gov. Mike Huckabee

Says securing borders must be a top priority and has reached the level of a national emergency. Supports the $3 billion the Senate has voted for border security. Says people caught trying to enter the United States illegally must be detained, processed and deported. Opposes giving driver's licenses to illegal immigrants and supports legislation to prevent states from doing so.

Arizona Sen. John McCain

Initially supported temporary guest worker program for illegal immigrants but has since shifted his position to emphasize border security first.

Former Massachusetts Gov. Mitt Romney

Backs securing the border with a wall, fence or electronic surveillance. Urges creating a biometric documentation program and establishing a verification system. Supports an increase in legal immigration into the United States and opposes compromise on immigration amnesty. Against driver's licenses for illegal immigrants.

Former Tennessee Sen. Fred Thompson

Opposes providing any legal status to illegal immigrants and urges tougher enforcement against them and their employers. Backs cutting off federal funds to cities that try to restrict communications with the Department of Homeland Security about an individual's immigration status. Urges finishing border wall by 2010, expanding Border Patrol to at least 25,000, making English the official language and improving the legal immigration process.

SOURCES: campaign Web sites and appearances.

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online here)

(Writing by Jeremy Pelofsky and Paul Grant)