Biden: Yes. In May, gave commencement speech at University of South Carolina and headlined Democratic fundraiser, first visit since he spoke at state party's annual fundraiser a year earlier. Several earlier visits since 2009.
Clinton: No, but things are stirring. At a May meeting in Columbia partly sponsored by Ready for Hillary, Virginia Sen. Tim Kaine urged Democratic women to "think about pledging your support right now" to ensure she has "millions of us ready to take the field with her" if she runs.
O'Malley: Yes, 2013 speech to party activists.
Bush: Yes, 2012 speech.
Christie: Yes, helped Mitt Romney raise money in 2012.
Cruz: Yes, speech at The Citadel military college in April was third visit in a year, following event with religious conservatives in November and speech to annual state GOP dinner last May.
Jindal: Yes, third visit in a year coming in June, as keynote speaker at state GOP's biggest gathering, the Silver Elephant dinner.
Paul: Yes, foreign policy speech at The Citadel military college and small GOP fundraiser in Charleston in November 2013 visit; headlined several fundraisers earlier in year.
Perry: Yes, two-day visit in December 2013, addressed state GOP. In August, raised money for Gov. Nikki Haley's re-election campaign.
Rubio: Yes, headlined 2012 Silver Elephant dinner.
Ryan: Yes, in 2012 campaign.
Santorum: Yes, April GOP event at The Citadel military college, where two sons are cadets. Campaigned in April 2013 for Curtis Bostic in GOP House runoff race; Bostic lost.
Walker: Yes, attended August fundraiser for Haley, who came to Wisconsin to campaign for him in 2012 recall vote.
GO ABROAD: Helps to give neophytes foreign policy cred, and Israel is a touchstone for U.S. politicians.
Biden: You bet. Visited Ukrainian capital in April to symbolize U.S. commitment to new government in its struggle against pro-Russian insurgents and threatening signals from Moscow. Brazil coming up in June. Long at forefront of Obama administration's diplomatic maneuvers with Kiev. Sent to Poland and Lithuania in March to reassure NATO allies anxious about Russia's annexation of Crimea. December 2013 visits to China, Japan and South Korea. Countless trips to Iraq and Afghanistan during first term.