Palmetto state insiders say Haley's support from voters has dwindled since her 2010 election, which was made possible from support by conservative tea partiers. Given that, was her decision to endorse someone not well liked by her former base—and not even the front-runner in South Carolina—risky?
Probably so, says one GOP operative from South Carolina.
"A lot of tea party/libertarian Republicans supported her for governor; she's in a very precarious spot now with them and with the mainstream business community too," he says. "She's straddling a line and not doing a very good job of it right now. She's going to have some problems down the road."
But the very fact that she's politically vulnerable may have led her to endorse Romney, he adds. Because if Romney wins the GOP nomination and is elected president, "he can come campaign for her in 2014 which allays a lot of the problems she has with the business community."
Charles Bierbauer, dean of the University of South Carolina's College of Mass Communications and Information Studies, says there could be other motivations as well.
"Her numbers are down; I think she's seen the lay of the land here," he says. "Maybe she even sees herself as a Romney-Haley ticket, though that's pretty far-fetched at this point. That's such rampant speculation."
And Haley might face some competition—Romney himself, soon after winning the endorsement of New Hampshire U.S. Sen. Kelly Ayotte, proclaimed that she would make a great running mate.