US election 2012: Rick Santorum bows out, clearing way for Mitt Romney While it became clear in recent weeks that Mr Romney's lead in delegates to the party convention was practically insurmountable, Mr Santorum had vowed to fight on until August's gathering in Florida. Newt Gingrich, a former House Speaker, and Ron Paul, a Texas congressman - both of whom trailed Mr Santorum - last night pledged to remain in the race until the convention. An ultraconservative evangelical Catholic who was initially dismissed as a fringe candidate, Mr Santorum, 53, embarked on a shoestring campaign for the Iowa caucus, the contest's first vote. The former Pennsylvania senator, who drove from rally to rally in a pickup truck, won the January poll but only after a recount, meaning that he was denied the boost in support it might have prompted. That momentum instead gathered behind Mr Romney, the long-standing front-runner, who was initially named the winner of the Iowa poll and used his vastly superior finances to continue building on his lead. As other Right-wing alternatives to Mr Romney rose and fell, Mr Santorum survived to win 10 more state primaries around the US. His strident moral tone on issues such as abortion and contraception attracted evangelical voters yet also alienated moderates and concerned the party establishment. Mr Santorum last night defended his decision to focus on the elements of the "moral enterprise that is America" that "somehow get pushed aside in the public discourse." In the end, his unconventional campaign, epitomised by the unfashionable knitted tank-top that he wore on the campaign trail, was simply obliterated by the Romney machine. Mr Santorum raised just $15.7 million (£9.9 million), a fraction of the $75 million (£47.7 million) haul brought in by Mr Romney, a comparatively moderate former Massachusetts governor. At the same time Restore Our Future, the external "super PAC" backing Mr Romney, has been able to lavish millions of dollars on television attack advertising against Mr Santorum and Mr Gingrich. In a swing at Mr Romney, Mr Santorum claimed that he had presented a "positive and hopeful vision for our country" instead of rubbishing fellow Republicans from the start. He said that his three-year-old daughter Bella, who suffers from a rare genetic condition called Trisomy 18 and was admitted to hospital last weekend, was "doing exceptionally well and is back with us."