Republicans Spar In US Presidential Race

The battle for the chance to take on Barack Obama in next year's US Presidential election is shaping up as a two-horse race following the latest Republican debate.

Eight candidates faced off over national security and foreign policy in Washington's Constitution Hall, just half a mile from the White House.

Former Speaker of the House of Representatives Newt Gingrich , who has surged to the top of the polls in recent weeks, maintained that momentum with a composed performance.

He is now regarded as a front-runner alongside former Massachusetts governor Mitt Romney .

The debate, the 11th so far, featured sharp exchanges on a broad range of issues, including anti-terrorism laws, Iran, Pakistan and Afghanistan.

Gingrich said that ending petrol sales to Iran and sabotaging its refineries would lead to the collapse of the Iranian government and end its nuclear ambitions.

He said: "I think it is a good idea if you're serious about stopping them from having nuclear weapons. I think replacing the regime before they get a nuclear weapon beats replacing the regime with a war which beats allowing them to have a nuclear weapon."

This was the second debate in less than two weeks to focus on foreign affairs in a race otherwise dominated by domestic issues. Republicans see the weak US economy as President Barack Obama's biggest vulnerability .

The candidates also sparred over how far America should go in sacrificing liberty in order to prevent terrorist attacks.

And they discussed the possible cuts to America's military which could result from the failure of the super committee to agree a deficit reduction deal.

Romney opposed the cuts, suggesting the money taken from the military would be used to fund Obama's controversial health care programme.

The debate came six weeks before voters in Iowa go to the polls. Romney has led the race for most of the year but has been unable to expand his support beyond the 25 percent level.

Meanwhile a series of rivals, including congresswomen Michele Bachmann, Texas governor Rick Perry and businessman Herman Cain, have surged to the top only to fade.

Despite his surge, Gingrich is facing questions about his divorces, extramarital affairs and business dealings, his past views on climate change and other issues could be seen as too moderate for some conservatives.

Political analyst James Carofino told Sky News: "Things are going to look very different when the new President puts his hand on the bible in 18 months time. This is about these candidates showing they can be leaders. The American people know more about them now."

Rick Santorum attracted most controversy in the latest debate by suggesting that Muslims should be singled out for 'profiling' as part of counter-terrorism efforts.