Voters in South Carolina's primary today showed a preference for picking a candidate who can beat President Obama, according to preliminary exit polls.

Also, more than half of voters said they hadn't made a choice until the last few days, according to the polls. And as expected, evangelicals turned out in large numbers.

"By wide margins, voters say they are primarily interested in a candidate who can defeat Barack Obama - nearly half call it the top candidate attribute, vs. two in 10 who are looking chiefly for the candidate with the best experience and fewer than that who've focused chiefly on the candidates moral character or conservative credentials," said ABC News' Gary Langer, of Langer Research Associates. "More cite electability as their top issue than did so in either Iowa or New Hampshire."

One finding sheds light on the effect that attacks on Mitt Romney's tenure at Bain Capital has had: Two-thirds of voters said his background is generally positive, and only 27 percent said they viewed it negatively.

"Nearly four in 10 describe themselves as 'very' conservative. That's more than in New Hampshire (21 percent) but fewer than in Iowa (47 percent)," Langer said. "Just over a third also describe themselves as strong supporters of the tea party movement - again substantially more than in New Hampshire, although about the same as in Iowa."