|Thursday's debate was the Republican candidates' final chance to impress before January's Iowa caucus [Reuters]
Candidates for the Republican Party's candidacy for next year's US presidential election have clashed in the final televised debate before the beginning of the primaries season, with Newt Gingrich and Mitt Romney vying for frontrunner status.
The two men considered the likeliest challengers to Barack Obama in November used Thursday's encounter to attack the incumbent US president's track record on foreign policy as they sought to make an impact ahead of the Iowa caucus, the traditional start of the presidential race, on January 3.
Romney, the former governor of Massachusetts, criticised Obama for trying to "appease or accommodate the tyrants of the world" and cited his weak response in trying to retrieve a drone brought down in Iran.
Gingrich, a former speaker in the House of Representatives who led most national opinion polls going into the debate, said: "I can debate Barack Obama and I think, in seven three-hour debates, Barack Obama will not have a leg to stand on in trying to defend a record that is terrible and an ideology that is radical."
But other candidates took aim at Gingrich over claims that he had profited from the former mortgage giant Freddie Mac, which critics say helped fuel the subprime home loans boom blamed by some for triggering the 2008 financial crisis.
"The evidence is Gingrich took $1.6m. You don't need to be a lobbyist to still have influence among Republicans in DC. And the bidding was to keep the scam of Freddie Mac going," said Michele Bachmann, a Minnesota Congresswoman. "That is something our nominee can't stand for."
Gingrich: I never lobbied
Gingrich denied the allegations saying he "never lobbied under any circumstance".
"I want to state unequivocally for every person watching tonight: I have never once changed my positions because of any kind of payment," he said.
Thursday's showdown in Sioux City, Iowa, also featured Rick Perry, the governor of Texas; Jon Huntsman, a former Utah governor; Ron Paul, a Republican representative from Texas, and Rick Santorum, a Pennsylvania senator.
Paul, a staunch fiscal conservative and critic of big government who came into the debate rising in the polls, staged a strong defence of his anti-war views by stating that he would not go to war with Iran if there was proof the country had developed a nuclear weapon.
"My fear is it's another Iraq coming," Paul said. "There's a lot of war propaganda going on."
Gingrich has topped most national opinion polls but a survey in Iowa before Thursday's debate saw his support in the state slip by 12 points to 20 per cent, with Romney on top with 23 per cent.
Polls show Romney also has a commanding lead in New Hampshire, which votes on January 10. The next contest is in conservative South Carolina, followed by the big battleground state of Florida.