FACTBOX: Obama and Huckabee on key issues

(Reuters) - Barack Obama won the most support from Democratic voters in Iowa on Thursday while Mike Huckabee won the Republican contest, putting both men closer to winning their parties' nomination for U.S. president.

Here are the two candidates' positions on several key issues in the campaign:

IRAQ

Huckabee: Opposes setting a timetable for troop withdrawal and says the "surge" in U.S. troops in Iraq helps foster reconciliation among Iraqis. He has criticized the Bush administration's foreign policy for an "arrogant bunker mentality".

Obama: Wants to begin immediately withdrawing one or two brigades a month and have all troops out within 16 months; would call a U.N.-led constitutional convention in Iraq that would not adjourn until reconciliation reached; aims to refocus energies on al Qaeda threat in Afghanistan and Pakistan;

IMMIGRATION

Huckabee: Opposes granting amnesty to illegal immigrants or granting driver's licenses to them; says those caught illegally entering the United States must be detained, processed and deported;

Obama: backs boosting the number of immigrants allowed in the United States; would permit undocumented workers to pay a fine, go to the end of the line for citizenship and learn English in order to stay in the country; would add personnel and technology to protect the U.S. borders.

HOUSING CRISIS

Huckabee: Has said market forces will correct the current mortgage crisis and that a government effort to help troubled homeowners could unfairly help imprudent borrowers and lenders.

Obama: Offered legislation aimed at setting a national standard for mortgage fraud and boosting penalties for such activities.

TRADE

Huckabee: Says the United States must fight unfair foreign competition that is costing American jobs, but globalization can be a "blessing" because it lowers prices of consumer goods.

Criticizes China for manipulating its currency to boost exports and discourage imports.

Obama: Pledges to renegotiate the North American Free Trade Agreement and other U.S. trade agreements to include strong, enforceable labor and environmental provisions.

Wants to revamp fast-track trade negotiating authority to require pre-screening of potential U.S. free trade partners based on their labor and environmental standards and other factors. Promises to get tough on trade with China and pressure Beijing to stop manipulating its currency.

CLIMATE CHANGE

Huckabee: Backs an unspecified cap on carbon emissions and 35 mile-per-gallon fuel efficiency standard by 2020; favors alternative energy and energy independence.

Obama: Wants to lead an effort to impose caps on carbon emissions and prompt U.S. automakers to build cars that use less oil; aims to implement an economy-wide "cap-and-trade" program to reduce greenhouse gas emissions.

TAXES

Huckabee: Would replace federal income and payroll taxes with a national sales tax. Would provide a monthly rebate to poor people to offset the tax on purchases.

Obama: Wants up to $85 billion in tax breaks for 150 million Americans financed by increasing capital gains tax and dividend taxes on wealthy; would eliminate corporate tax loopholes and offshore tax havens.

(Compiled by Jeff Mason and Jeremy Pelofsky in Washington; editing by Stuart Grudgings)

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