The current front-runner, Romney, who won 11 states' primaries and caucuses before dropping out of the 2008 Republican campaign, has never really stopped campaigning. Romney, 60, has already hired a team of staff members and consultants and his Free and Strong America political action committee recently has raised $2.1 million. The Hill recently noted that "history is on Romney's side" in that four of the past five Republican presidential nominees had previously lost the nomination, and commented that the work Romney has already done "paints a promising portrait of Romney’s prospects for 2012." As the former CEO of Bain & Company, the prestigious management consulting firm, Romney's campaign for the nomination might be unstoppable if the country's economic woes don't abate.

Pawlenty, who was co-chairman of John McCain's 2008 presidential campaign, announced earlier this year that he would not seek a third term as Minnesota's governor in 2010. Pawlenty, 48, recently signaled his intentions for 2012 by filing paperwork with federal regulators to form his Freedom First political action committee and bringing on a team of experienced Republican campaign consultants. In an interview with The Washington Times last month, the former Minnesota state representative "sounded most of the right base notes as a Republican who is clearly eyeing the 2012 presidential nomination."

Like Romney, Huckabee, 54, who finished second in the 2008 Republican presidential primaries, has effectively turned his 2008 campaign into one for 2012. The ordained minister's folksy brand of Christian conservatism played well with the Republican base, although it also raised questions about his overall electability. Huckabee easily won an early straw poll of the run by the Family Research Council and conservative political consultant John Feehery, writing for The Hill's Pundit's Blog, recently noted about Huckabee: "If I were to put money down on the favorite to win the Republican primary, I would put it on Mike Huckabee right now." While Huckabee might be the favorite now, The Top 13 would take that bet.

In his second term as Mississippi's Governor, Barbour, 62, is barred by term limits from running again. As Chairman of the Republican National Committee between 1993 and 1997, the former lawyer and lobbyist oversaw the Republicans capturing both the Senate and House of Representatives for the first time since 1954. Earlier this year, he began testing the waters for 2012 with several fundraising trips and speeches at GOP functions. Conservative political consultant John Feehery, writing for The Hill's Pundit's Blog, recently called Barbour "probably the best natural politician that Republicans have on their team now" and noted that he "is very, very popular with the Republican base." If the GOP doesn't go with a reformer, Barbour will be a 2012 front-runner.

In the midst of his first term as Louisiana's governor, Jindal, only 38, is considered a GOP rising star. Jindal, who advised Fortune 500 companies at the consulting firm McKinsey & Co. before entering public service in his mid-20s, served two terms in the U.S. House of Representatives before a successful bid for governor in 2007. Jindal's reputation took a massive hit when he delivered the official Republican response to President Obama's first speech to a joint session of Congress earlier this year. The New York Times noted that conservative commentators were "among the harshest critics, calling Mr. Jindal's delivery animatronic, his prose 'cheesy' and his message . . . uninspired." Still, Jindal has time to rehabilitate himself as a candidate, particularly among the GOP's more conservative voters, who approve of his social positions and value the youth and diversity Jindal could bring to a 2012 campaign against Obama.

Gingrich, who served as Speaker of the U.S. House of Representatives from 1995 to 1999, is best known as an author of the controversial Contract with America and the leader of the Republican Revolution in the House, which ended forty years of Republican minority. Since leaving the House in 1999, Gingrich, 66, has served as a fellow at several conservative think tanks. Here's what The Atlantic has said about the possibility of Gingrich in 2012: "He wants it, clearly, and is already planting some seeds in Iowa and New Hampshire. Though he is deeply polarizing within the country and within his party, he'll be instantly credible as a candidate because of his stature and his financial backing, and you can't say the guy lacks ideas."

Palin, who recently resigned as Alaskan governor, burst onto the national scene as 2008 Republican nominee John McCain's running mate. The "Draft Palin" for 2012 movement began even before President Obama moved into the White House, and despite numerous hits to her public perception (don't forget, she can see Russia from Alaska), Palin, 45, is still considered a viable candidate by some in the conservative corners of the GOP. McCain recently agreed, telling CNN: "When we selected or asked Sarah Palin to be my running mate, it energized our party. We were ahead in the polls, until the stock market crashed. And she still is a formidable force in the Republican Party."

General Petraeus, 57, assumed command of the U.S. Central Command just over a year ago and is in charge of U.S. military operations in 20 countries, including in Iraq and Afghanistan. Petraeus, from New Hampshire, has a Ph.D. in International Relations from Princeton University and, according to The New Yorker, has described himself as a "northeastern Republican, in the tradition of Nelson Rockefeller." Although Petraeus has denied having political aspirations, The New York Times wrote last month about growing speculation about the general’s possible candidacy. The paper quoted an Ohio State University professor of military history: "It is other people who are looking at his popularity and saying that he would be a good presidential candidate, and I think rightly that makes the administration a little suspicious of him." Petraeus could move quickly up this list over the next year or so.

Earlier this year, Bush, the younger brother of George W. Bush, announced that he would not run for the U.S. Senate next year. If anything, the announcement by Bush, 56, has increased speculation that he'll try to become the third Bush to occupy the White House. Only time will tell if George W.'s unpopularity will limit Jeb's political aspirations, but there is no question that the younger Bush is better suited for the presidency than his older brother. Writing for The Daily Beast earlier this year, New America Foundation fellow Reihan Salam posited that Bush is "the GOP's best hope for beating Obama." Salam explained that Bush is "a successful two-term governor of a big swing state with sterling conservative credentials, a record of appealing to Latino voters, and the raw brainpower and rhetorical skill to match Barack Obama."

Perhaps the most socially conservative of The Top 13's 2012 Republican Presidential Hopefuls, Santorum, 51, also has been among the most open of the potential candidates about his intention to run. Santorum served two terms in the U.S. Senate before falling short in his bid for another six years in 2006, losing by the biggest margin of defeat for an incumbent senator since 1980. Santorum, who currently works as a lawyer and a fellow at a conservative think tank, has been making the rounds in early caucus and primary states like Iowa since the summer. According to Politico.com, during an interview in Iowa in August, Santorum hinted at his plans when asked whether his conservative profile would fit the state: "One of the things we've seen from the Iowa caucuses is candidates that appeal to the base do very well. I think historically that's always been sort of a key in Iowa. Whether I do or not, I don't know – I mean, we’ll see."

Giuliani may still have presidential aspirations, but after his disappointing performance in the 2008 Republican primaries, it's highly doubtful he'd subject himself to another national campaign. Besides, Giuliani, 65, very well might preempt this discussion altogether by deciding to run against incumbent David Paterson for governor of New York next year. If he does decide to seek the Republican nomination in 2012, the former New York City mayor likely would be able to reassemble his 2008 campaign team and could be formidable, as he continues to trade on his career-making moment as New York City's chief executive on 9/11. Still, Giuliani’s perceived personal foibles and ethics issues make him a long-shot to emerge as the Republican candidate.

The candidate most likely to carry the torch for supporters of Ron Paul's libertarian movement, Johnson, 56, has already indicated his interest in the Republican nomination. The former two-term New Mexico governor has been largely out of the spotlight since leaving the statehouse in 2003, but actively supported Paul's candidacy in 2008 and has spent the past few months successfully building up grassroots libertarian support. Even tried and true libertarians, however, recognize the limitations in a Johnson candidacy. During his second term as governor, Johnson came out strongly against the war on drugs, and his views on legalization often overshadow his stances against the Iraq war and in favor of limited government, while making him vulnerable to attack from the right. Johnson won't win the nomination, but, like Paul, he could force his fellow candidates to focus on issues that are typically ignored during presidential campaign.

Rice, who served as Secretary of State and National Security Advisor in the Bush administration, is currently a political science professor at Stanford (where she was provost from 1993 to 1999) and a senior fellow on public policy at the Hoover Institute. Rice, 54, was rumored to be considering a run for the Republican nomination in 2008. However, she ended that speculation during an interview in February 2008 with Meet the Press: "I have always said that the one thing that I have not seen myself doing is running for elected office in the United States." Nevertheless, Rice, a former Democrat, was considered a serious candidate to be selected as John McCain’s running mate. And while Rice has not signaled any interest in running in 2012, that hasn’t stopped the speculation about her intentions or the proliferation of Rice in 2012 Facebook groups. Like Jeb Bush, however, Rice very well may struggle to overcome the legacy of former President George W. Bush’s two terms.