FACTBOX: Candidates McCain and Clinton on key issues

(Reuters) - Democratic Sen. Hillary Clinton and Republican Sen. John McCain won their parties' primaries in New Hampshire on Tuesday, the second high-profile battleground in the state-by-state contests to choose candidates for the November presidential election.

Here are McCain's and Clinton's positions on several key issues in the campaign:

IRAQ

McCain has been a staunch supporter of the Iraq war and, particularly, the "surge" in troops there. A Vietnam War veteran and former POW, he has said he would rather lose an election than lose the war.

Clinton has taken heat for her initial vote in favor of authorizing the war. Became a sharp critic of President George W. Bush's handling of the conflict and says as president she would start bringing troops home.

IMMIGRATION

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

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. Supported the building of a border wall. Urges development of an employer verification system and higher penalties for employers who exploit illegal immigrants.

CLIMATE CHANGE

McCain has advocated a system that would cap emissions of carbon dioxide, the main gas blamed for global warming, and allow big polluters to trade rights to emit. He co-authored a bill to cut emissions by 65 percent by 2050.

Clinton supports an 80 percent reduction in carbon emissions by 2050, 40-mile-per-gallon fuel efficiency standard by 2017 and 10 percent cut in energy consumption by 2020.

TAXES

McCain says taxes should be low, simple and fair. Advocates lower tax rates and spending cuts.

Clinton's health-care plan includes some new tax credits and she says she would roll back some of Bush's tax cuts for top income earners. Also proposes new tax breaks for retirement savings.

(Compiled by Jeff Mason in Manchester, New Hampshire; editing by Eric Beech)

((jeff.mason@reuters.com, +1 202 310 5487, Reuters Messaging: jeff.mason.reuters.com@reuters.net)