Republican candidates - Mitt Romney
With the primary season in full swing, the BBC looks at the Republican candidates seeking to stand against President Barack Obama in November.
Mitt Romney made a respectable run for the Republican nomination in 2008 - and never quite left the campaign trail.
The 2012 race began with the wealthy former Massachusetts governor the presumed front-runner, a status he has never firmly relinquished.
Mr Romney hopes his background in business will help him convince voters he can manage America's slow economic recovery better than President Obama - or other Republicans in the field.
But his narrow victory in Iowa's caucuses did not appear to have quelled doubts among the Republican electorate about his conservative credentials.
The Romney campaign and its backers have spent large sums - $53m by early April - on advertising in the primary season.
After a string of primary wins, Mr Romney has built up a significant lead in delegates and the Republican establishment has started to coalesce behind him.
However, some evangelical Christians influential in the Republican race are uncomfortable with his Mormon religion.
Before serving a term as governor of Massachusetts, Mr Romney was the head of the 2002 Salt Lake City winter Olympics, and the successful head of a private equity firm.
See a fullprofile of Mitt Romney.