Washington: The battle for the 2012 Republican presidential nomination heats up on Thursday with the entry of default front-runner Mitt Romney into a race devoid of a clear favorite.
In prepared remarks released ahead of announcing his candidacy, the ex-governor of Massachusetts said that President Barack Obama "has failed America," and vowed to increase the country`s job growth.
Considered next-in-line after losing the 2008 nomination to Senator John McCain, strong name recognition has helped Romney, 64, top many early opinion polls, albeit by slim margins in a tightly-bunched field.
In 2008 voters "gave someone new a chance to lead; someone we hadn`t known for very long, who didn`t have much of a record but promised to lead us to a better place," Romney said.
"Now, in the third year of his four-year term, we have more than promises and slogans to go by. Barack Obama has failed America."
As president, Romney said he would cap federal spending at 20 percent or less of the GDP "and finally, finally balance the budget. My generation will pass the torch to the next generation, not a bill," he said.
Romney makes his candidacy official at 1630 GMT at a campaign event on a farm in the state of New Hampshire.
Democrats immediately hit back, releasing a video portraying Romney as a politician who is constantly changing his views. The video featured Romney video clips giving divergent opinions on key policy matters.
"Romney 2012. Same candidate. Different positions. Again," is the video tagline.
Romney`s opponents rarely miss a chance to dig at his Achilles` heel -- a state health care overhaul that served as an inspiration for Obama`s reforms, which are anathema to core Republican voters.
Romney also faces an uphill battle to overcome deep suspicion of his Mormon faith among the Christian right, many of whom consider the Church of Jesus Christ of Latter Day Saints, as it is officially known, heretical.
Contributing to his 2008 nomination failure were doubts from core conservatives that he truly shared their values, as well as questions fueled by his moderate governing style in deeply liberal Massachusetts.
After railing against gay marriage and vowing to cut taxes and crack down on illegal immigration, Romney was forced to deny claims he was simply a "flip-flopper" who was ditching previously held liberal positions.
A Boston venture capitalist and founder of a management consultancy, Romney first entered politics in 1994 when he unsuccessfully stood against prominent Democrat Ted Kennedy for Massachusetts senator.
In 1999 he was brought in to rescue the 2002 Winter Olympics in Salt Lake City, which had become mired in scandal.
He saved the games from financial ruin, then translated the experience into a successful bid for the Massachusetts governorship in 2002.
Republican grandees worry the crowded field of possible White House hopefuls could end up helping Obama, who is vulnerable as the economy sputters its way out of the worst downturn since the Great Depression of the 1930s.
Former Minnesota governor Tim Pawlenty and former House speaker Newt Gingrich are the highest-profile Republican candidates to have declared their 2012 candidacy thus far.
Ex-ambassador to China Jon Huntsman, a former governor of Utah, is expected to throw his hat into the ring, as is Minnesota congresswoman Michele Bachmann, a flag-bearer of the conservative and libertarian Tea Party movement.
The biggest hype surrounds the possible candidacy of former Alaska governor Sarah Palin, McCain`s surprise running-mate pick in 2008.
An ongoing "One Nation" bus tour along the eastern seaboard is fueling speculation that Palin -- who has a canny grass-roots focus and a genius for milking media attention -- will jump into the Republican field.
Palin dined on Tuesday in New York with another outsized and controversial conservative character, Donald Trump, the bombastic real estate mogul and reality television star who dropped his flirtation with a bid last month.
There is no clear favorite in the complex and confusing Republican race.
Top of a recent CNN poll was former New York mayor Rudy Giuliani, who has not ruled out a 2012 bid and is also in New Hampshire on Thursday for a Republican fund-raising event.
Former Arkansas governor Mike Huckabee, who finished second in delegate count to McCain in 2008, disappointed supporters last month by saying no, but reportedly rowed back Wednesday and suggested he could still run.