South Carolina undercuts Romney's electability argument The South Carolina Republican Party's mantra is: "We pick presidents." Voters in Saturday's primary felt the same way, but their idea of who was most electable differed starkly from their predecessors in the 2012 GOP presidential race. By the end of the contest Saturday, exit polls show Mitt Romney's reputation as the most electable Republican candidate took a severe blow. Romney, whose performances in Iowa and South Carolina were spurred in large part by voters who were looking for the candidate best equipped to beat President Obama in November, saw his support among this group plummet in South Carolina. According to exit polls, nearly half of voters said beating Obama was the main factor in their choice, and among those voters, Gingrich took about half the vote, beating Romney by more than 10 percent. In Iowa and New Hampshire, by contrast, Romney carried this group by 28 and 51 points, respectively. In the Granite state, Romney won six out of 10 voters who said electability was the most important factor; next was Gingrich at just more than one in 10 voters. South Carolina is just one state, but the fact that what is arguably Romney's strongest attribute - his electability - has been called into question should be a cause of great concern for his supporters. All along, as conservatives have balked at embracing the former Massachusetts governor, the counter-argument has been: well, he's the most conservative candidate who can beat Obama. Following Gingrich's strong performance in Monday's debate, that argument has been undermined. All of a sudden, voters who were prepared to vote for Romney - he led the state by double digits in the polls a week ago - decided Gingrich is their better hope against Obama. And if voters in other states start to feel the same way, Romney's path to victory becomes immensely more difficult. Get more news & analysis from PostPolitics: Gingrich comes from behind to win South Carolina S.C. voters liked Gingrich's 'guts' Exit polls find that ability to beat Obama is most important quality How Gingrich's past marriages may be helping him in S.C.