WASHINGTON (Reuters) - Big-name Republicans are maneuvering for their party's presidential nomination in 2012 to try to deny Democratic President Barack Obama a second four-year term.
Here is a list of prominent Republicans who are seriously considering a run for the White House.
If there is a Republican front-runner, Romney is probably it. He was outdueled by John McCain in the 2008 Republican race but has since been plotting a return.
The former Massachusetts governor has been on a cross-country blitz to meet wealthy, well-networked donors and announced earlier this month he would set up an exploratory committee to begin raising money for a candidacy.
Romney has a strong organization and has touted his business experience as a way to attack Obama's stewardship of the U.S. economy.
A weak spot for Romney is the healthcare plan he helped develop for Massachusetts because it bears a strong resemblance to the Obama healthcare overhaul that conservatives want to repeal.
Romney took the problem head-on in a speech in New Hampshire this year, saying the approach he used was specific for Massachusetts and would not work as a national policy.
"Our experiment wasn't perfect -- some things worked, some didn't and some things I'd change. One thing I would never do is to usurp the constitutional power of states with a one-size-fits-all federal takeover," he said.
Known for his success in the world of finance, Romney has a personal fortune estimated in 2008 at $190 million to $250 million. But critics say he caused job losses as a corporate raider.
He has been leading opinion polls in New Hampshire, where he has a vacation home that gives him a natural advantage in the state's key primary next year.
A Mormon, Romney might struggle to win support from conservative Republicans in the South.
The 2008 Republican vice presidential nominee has major star power in the Republican Party. Since resigning as governor of Alaska in 2009, she has made herself a millionaire with two books, a TV show called "Sarah Palin's Alaska" and many speaking engagements.
A leading voice in the fiscally conservative, anti-establishment Tea Party movement, she enhanced her influence by campaigning for its candidates across the country in last year's congressional elections.
But some Republican heavyweights are leery of Palin because she is a polarizing figure and her support seems limited to conservatives. In a self-inflicted wound, she sparked a controversy with comments about a media "blood libel" against her after a U.S. congresswoman and several other people were shot in Arizona in January.
Palin traveled to India and Israel last month to beef up on foreign policy. She is still keeping her supporters guessing on whether she will run.
"I'm not saying it's going to be me offering my name up in the name of service," she said in February. "There is so much to be considered but I certainly believe that this is going to be an unconventional political cycle."
Palin has no timetable for deciding on whether to run but if she does decide to give it a try, she might leave it until late because she already has name recognition.
The former Minnesota governor came on the national stage in 2008 when he was on John McCain's short list to be the Republican vice presidential candidate.
"T-Paw" -- as he is known by his supporters -- was a popular governor in a state that has seen big political swings over the years.
Pawlenty won plaudits for eliminating a $4.3 billion state budget deficit without raising taxes and has been a staunch voice against abortion and stem-cell research. Critics say he lacks charisma.
In "Courage to Stand," a memoir timed to coincide with his expected campaign, Pawlenty denounced "runaway spending" in Washington and blamed Obama for a mountain of debt.
Pawlenty announced on March 21 that he would set up a presidential exploratory committee, a formal step toward running for the Republican nomination. He was the first senior Republican to do so.
The representative from Minnesota is a leading figure in the Tea Party movement that helped Republicans win the House of Representatives from Democrats last year.
First elected to Congress in 2006, Bachmann rose to prominence in the Tea Party movement during the 2010 midterm election with her attacks on the Obama administration.
She is seen as someone who would benefit if Palin decides not to run, as the two appear similar in politics and personality.
Bachmann is planning to file papers to form a presidential exploratory committee by June.
The governor of Indiana generated a lot of enthusiasm in conservative circles with a speech in which he compared the U.S. fiscal situation to the "red menace" the United States fought during the Cold War.
"The second worst outcome I can imagine for next year would be to lose to the current president and subject the nation to what might be a fatal last dose of statism," he said. "The worst would be to win the election and then prove ourselves incapable of turning the ship of state before it went on the rocks, with us at the helm."
Daniels is considered a highly competent manager and all-around smart operator. He was budget director for Republican President George W. Bush.
But Daniels lacks pizzazz in a party that needs an energetic performer, although he gave a well-received comical speech at the Gridiron Club's dinner of skit and song in Washington before an audience of reporters and VIPs.
Daniels is expected to make up his mind on whether he will run soon. He had said he would wait until this week's end of the Indiana legislative session.
The former speaker of the House was the main architect of the 1994 Republican congressional election victory and author of the "Contract with America" political manifesto. But the Georgian ended his 20-year congressional career after Republican losses in the 1998 elections.
Gingrich remains a leading conservative figure, political pundit and accomplished fund-raiser. He strode into the Conservative Political Action Conference to the tune of the "Rocky" movie theme, "Eye of the Tiger," and offered a blistering critique of Obama.
Gingrich told a conference call of key supporters that he hoped to announce a presidential bid in May at Philadelphia's Independence Hall.
Distinguishing himself as a conservative who is "not angry," the former Arkansas governor used a mixture of anti-abortion, anti-gay politics and regular-guy charm to win the 2008 Republican Iowa caucus against better-known candidates.
Huckabee, a Baptist minister with strong ties to conservative Christian groups, continues to poll well in Iowa and has been considered a potential presidential front-runner in 2012.
He is also dogged by controversy from decisions granting clemency to convicted criminals in Arkansas, including a felon who later allegedly killed four Washington state policemen and died in a gunfight with a Seattle officer.
His decision on a presidential run could be months away.
Huntsman annoyed the Obama White House by declaring his intention to resign at the end of April as U.S. ambassador to China and let it be known he is considering a race for the Republican presidential nomination.
Like Romney, Huntsman has roots in Utah and is Mormon. A former governor of Utah, Huntsman is a moderate Republican, which may make it difficult for him to win over conservatives who play a giant role in the nominating process.
Huntsman has a campaign-in-waiting in Horizon PAC, a political action committee that started a website and is seeking donations. It has hired veteran Republican operative John Weaver, McCain's senior adviser in his 2000 presidential campaign.
Huntsman is to decide when he returns from China at the end of this week.
Santorum announced earlier this month that he will set up an exploratory committee to pursue the Republican nomination. Santorum, once a top Senate Republican leader, was defeated in his 2006 re-election bid. A social conservative, he made a name for himself a decade ago by opposing abortion rights and gay marriage.
Paul, an anti-war Texas libertarian congressman who ran a failed 2008 campaign for president, said on Tuesday he would form an exploratory committee for a longshot bid for the 2012 Republican presidential nomination.
Paul built a loyal following of activist supporters in 2008 with his calls for cuts in defense spending and his criticism of the Federal Reserve's power and monetary policy.