Republican presidential candidate Rick Santorum has ended his bid for the White House, leaving Mitt¹ Romney as the presumptive nominee².

美国共和党总统候选人里克·桑托伦退出总统选举，使米特·罗姆尼成为预定候选人。

The former Pennsylvania senator made the announcement at a news conference in the city of Gettysburg.

"While this presidential race is over for me, we are not done fighting," said Mr Santorum, a social conservative.

He had been campaigning in Pennsylvania, his home state, ahead of its primary on 24 April.

But he was far behind Mr Romney in terms of funding and was in danger of losing the state for the second time in six years, analysts³ said.

In 2006 Mr Santorum lost his Pennsylvania Senate seat by an 18-point margin⁴.

In the current race for the Republican nomination⁵, Mr Santorum lags far behind Mr Romney in terms of the number of delegates needed to seal the nomination at the Republican convention in Tampa, Florida, in late August.

'Against all odds⁶'

Mr Santorum's children and his wife Karen stood behind him in Gettysburg as he made the announcement that he was suspending his campaign.

He had taken time off the campaign trail in recent days as his three-year-old daughter Isabella, who has a rare genetic⁷ disorder⁸, was admitted to hospital.

Mr Santorum proved to be the most resilient（有弹力的） of the Republican rivals challenging Mr Romney's front-runner status.

In his statement he said he had surpassed expectations, adding that "against all odds, we won 11 states, millions of voters, millions of votes".

"We were winning in a very different way," Mr Santorum said, "We were touching⁹ hearts."

He remembered some of the volunteers he worked with during the campaign.

Without the help of people like Wendy in Iowa, who made 5,000 phone calls or the girls in Tulsa, Oklahoma, whose song "Game On" became an internet sensation, the campaign would not have come as far as it did, Mr Santorum said.

Mr Santorum mentioned his visit to the factory of the Minnesota manufacturer of his sweater vests, which became known as the former Senator's signature outfit¹⁰.