Republican candidates - Rick Santorum
With the US primary season in full swing, the BBC looks at the Republican candidates that hoped to stand against President Barack Obama in November.
The former Pennsylvania senator withdrew from the Republican presidential race on 10 April after trailing Mitt Romney in the delegate count and losing a string of key state primaries.
Mr Santorum, a socially conservative Republican, had hoped to rally the party's base which felt dissatisfied with Mr Romney and establishment Republicans.
After lagging at the back of the pack for months, his solid social conservative credentials and hard work helped him surge to a narrow win in Iowa.
He then pulled off a hat-trick in Colorado, Missouri and Minnesota in February.
But losses in key states such as Michigan, Ohio and Wisconsin made his campaign vulnerable.
The dark horse's fundraising could not match Mr Romney's and he managed to secure just 285 delegates versus Mitt Romney's 661 before suspending his campaign.
Mr Santorum, 53, practised law before his election to the House of Representatives in 1990.
In 1994 he was elected to the Senate, where he made a name for himself as a fierce opponent of abortion and gay rights.
But he lost his 2006 re-election bid by 17 points.
Read Rick Santorum's .