Mitt Romney, the former Governor of Massachusetts, is the son of Republican Party politician George W. Romney. He is the only presidential candidate to have remained near the top of the polls throughout the race.
In the polls: The Des Moines Register released on Friday sees Romney with 24 per cent support -- 2 per cent ahead of Ron Paul. Romney's support in Iowa has grown by five points since an early December Time/CNN survey.
Main policies: Romney's policies emphasise "the principles of free enterprise, hard work, and innovation" and the reduction of taxes, spending regulation, and government programs. Pro-lifer Romney supports sentencing under the three strikes law and abstinence education in public schools, but has opposed the endorsement of any one religion or faith in public schools.
Major gaffes: Romney, who was recently described as "gaffe-proof" in the Harvard Political Review, has yet to make a Bachmann-style blunder in the GOP race.
The ultra-right policies of Tea Party darling Bachmann, from Minnesota's 6th Congressional District, have seen her branded Palin version 2.0 .
The presidential hopeful's top Iowa adviser Kent Sorenson announced last Wednesday night that he was jumping ship to support Ron Paul's candidacy.
In the polls: The RealClearPolitics latest polling average sees Bachmann with a sorry 6.2 per cent in Iowa. The Minnesota candidate's spirits did not seem to be dappened when she was seen out on Monday stating that her goal "is to be America's iron lady."
Main policies: Bachmann, who describes herself as a "constitutional conservative", lists the creation of new jobs, the repeal of Obamacare, the strengthening of family and the "defence of marriage" among her top priorities. Bachmann supports the teaching of creationism in public school science classes, is a strong proponent of nuclear power, and has identified herself as "100 per cent pro-life" -- including in cases of rape or incest. She has also called for the phasing out of social security and Medicare, and supports both a federal and state constitutional amendment banning same-sex marriage and legal equivalents.
Biggest gaffe: Bachmann wrongly identified her hometown to be that of movie star and American icon John Wayne back in June; in late November, she revealed plans to close the US Embassy in Iran  -- despite America not having one there since 1980.
Gingrich, a former Speaker of the U.S. House of Representatives from Georgia, is most widely identified with the 1994 Contract with America. Despite the en masse departure of a group of his senior campaign aides in June, Gingrich emerged as a GOP frontrunner in November.
Gingrich yesterday blamed his failure to get enough votes for Virginia's GOP presidential voting on a worker hired by his campaign.
"We hired somebody who turned in false signatures," he said at a campaign stop in Iowa, adding: "We turned in 11,100 -- we needed 10,000 -- 1,500 of them were by one guy who frankly committed fraud."
In the polls: Gingrich is currently in fourth place among the Republican candidates, collecting just 14 per cent of support, according to new CNN polls, whilst the Des Moines Register has him at 12 per cent.
Main policies: Gingrich has advocated replacing the Environmental Protection Agency with a proposed "Environmental Solutions Agency" and a flex-fuel mandate for cars sold in the U.S. He identified as pro-life and has proposed that high-school girls who graduate as virgins be rewarded.
Biggest gaffe: Gingrich was forced into damage-control mode after dismissing Rep. Paul Ryan's Medicare proposal as "right-wing social engineering" back in May.
Huntsman, a former US ambassador to China who identifies as a centre-right conservative, has been  called "a conservative technocrat-optimist with moderate positions".
In the polls: An average of several polls by RealClearPolitics puts Huntsman in last place with 2 per cent of the vote, whilst the CNN/Time/ORC poll has him with 1 per cent.
Main policies: As the governor of Utah, Huntsman signed supported legislation that would have allowed civil unions- but not marriages- for same-sex couples in the state.
Biggest gaffe: During an interview in October on The Colbert Report, Huntsman quipped "When's the delivery food coming?" when the show played a stereotypical Chinese musical jingle. The ill-advised joke was later cut from the show.
Paul, from Texas's 14th congressional district, has been variously termed both the "intellectual godfather" of the Tea Party movement and "Dr. No" -- a nickname reflecting both his background as an obstetrician and his assertion that he will "never vote for legislation unless the proposed measure is expressly authorized by the Constitution".
In the polls: A CNN/Time poll released on Wednesday placed Paul at 22 per cent, just 3 per cent behind Mitt Romney, while the Democratic firm Public Policy Polling survey shows Paul surging into first place with 24 per cent to Romney's 20 per cent.
Interestingly, according to a Rasmussen/University of New Hampshire poll, just 51 per cent of Paul supporters in Iowa consider themselves Republicans. In New Hampshire, the number is 56 percent.
Main policies: Paul lists limited, constitutional government, low taxes, free markets, and a pro-America foreign policy as priorities. Having maintained a consistent non-interventionist foreign policy stance, he opposed the Iraq war, broke with his party to vote against the Patriot Act, andadvocates withdrawal from the UN and from the North Atlantic Treaty Organization. Paul has also opposed the war on drugs and has called for passage of tax relief bills to reduce health care costs for families. He has described himself as "strongly pro-life".
Biggest gaffe: Paul stormed out of a interview with CNN earlier this month when questioned about racist newsletters that had been sent out under his name in the eighties and nineties.
Governor of Texas and self-described "long-time hunter" Perry persistently denied aspirations to higher office until 2011. His YouTube Presidential campaign video- which states "there's something wrong in this country when gays can serve openly in the military, and your kids can't openly celebrate Christmas"- sparked an online furore earlier this month.
In the polls: In the latest Gallup national tracking poll, Perry remained in the middle of the pack of presidential hopefuls at 8 per cent. A new CNN/Time Magazine poll out Wednesday had Perry in fifth place, while another Iowa poll by NBC News-Marist poll released on Thursday saw Perry with 14 per cent.
A climate change sceptic and staunch opponent of gay marriage, Perry has signed more pro-life legislation than any other governor in the history of Texas and advocates for a human life amendment to the U.S. Constitution.
Biggest gaffe: Perry couldn't recall his own policy  -- the Department of Energy being the third US government agency he would eliminate if elected -- during a televised debate in November.
Former Senator for Pennsylvania Santorum was dubbed "a Tea Party kind of guy before the Tea Party even existed" by the Washington Post.
In the polls: Santorum surged toward the top of the ballot in a CNN poll released Wednesday. The Iowa survey places the former Senator at 16 per cent- an impressive jump from sixth to third place. The Des Moines Register predicts that he might 'elbow' Ron Paul out for second place later this evening.
Main policies: Santorum, who describes himself as "a consistent full-spectrum conservative both in word and in action", has emphasised his pro-life stance and opposition of "taxpayer abuse and corruption in Washington" throughout his campaign.
Biggest gaffe: In a GOP debate in October, Santorum remarked: "I don't want to go to a trade war, I want to beat China. I want to go to war with China and make America the most attractive place in the world to do business."