In the crowded fight for the Republican presidential nomination, three well-known candidates have loyal followings, but trail far behind in opinion polls.

Michele Bachmann , a Republican U.S. Representative for the state of Minnesota, helped found the House Tea Party caucus. In August she became the first woman to win the Iowa straw poll, but her popularity was soon eclipsed by Texas Governor Rick Perry's entry into the race.

Trained as a tax attorney, Bachmann and her husband, clinical therapist Marcus Bachmann, run a Christian counseling center in Minnesota. The couple have five children and have fostered 23 others.

Bachmann, who is 55, is calling for deep cuts to government spending, and repeal of the health care reform law authored by the Obama administration. She also supports federal and state constitutional amendments that would ban same-sex marriage. She opposes abortion.

Bachmann has drawn fire for being combative in interviews and debates. Brian Darling of the Heritage Foundation says he believes that's an asset. “She doesn't sound like your average politician,” he says. “She's willing to get aggressive and fight and dig her heels in. And that's something Republicans want because they want to see a candidate to toe-to-toe with Barack Obama in debates.”

Jon Huntsman , 51, is a career diplomat and politician and a former governor of the western U.S. state of Utah. He has a degree in international politics and served in four U.S. presidential administrations: Ronald Reagan, George H.W. Bush, George W. Bush and Barack Obama.

Serving as the U.S. trade ambassador during the administration of George W. Bush, Huntsman helped negotiate trade agreements with Asian and African nations. Under President Obama, he served as U.S. ambassador to China until early 2011, when he stepped down to run for the presidency. He is fluent in Mandarin .

Huntsman and his wife, Mary Kaye, have seven children. Two of their daughters are adopted, one from China and the other from India.

Stephen Hess of the Brookings Institute says Huntsman is the only Republican candidate who “really has a serious work record” in foreign policy. But he also notes that, because of the dominance of economic concerns in this election cycle and the fact that U.S. President Barack Obama is seen as strong on foreign policy, the issue is not a major focus among Republican candidates.

Darling calls Huntsman “a very uninspiring candidate” whose agenda does not differ markedly from the more popular competitors. Darling also notes that some Republicans “can't forgive” Huntsman for serving in the Democratic Obama administration.

Rick Santorum , 53, is a former U.S. lawmaker from the eastern state of Pennsylvania. He and his wife Karen have seven children.

He has degrees in both business and law, and before entering politics he practiced law in Pennsylvania. He served two terms in the U.S. House of Representatives beginning in 1991 and was elected to the Senate in 1994. Santorum served two terms in the Senate before losing his seat in 2006.

His support levels are low, says Faiz Shakir of the Center for American Progress , partly because he lost that bid for re-election to Democrat Bob Casey.

Santorum “started from near zero and hasn't been able to climb out of that position,” says Shakir. He says that issue poses questions among Republicans about Santorum's viability as a candidate. Essentially, he says, Republican voters may wonder “why couldn't you even win a Senate seat,” before Santorum tries for the presidency.

Shakir says he thinks Santorum's real purpose in the race is to help push the party and campaign discussions toward his far-right positions, which include support for taking military action against Iran and opposition to gay rights and to abortion under all circumstances.