Exit polls: Bill Clinton's effect

[cnn-photo-caption image= http://i.l.cnn.net/cnn/2008/images/01/26/art.billclintoneff.gi.jpg caption=" Bill Clinton has campaigned heavily for his wife."]

(CNN) - Bill Clinton's aggressive campaigning in South Carolina in the days leading up to the state's primary may have had a net negative effect among South Carolina’s Democratic primary voters, CNN exit polls indicate.

Roughly 6 in 10 South Carolina Democratic primary voters said Bill Clinton's campaigning was important in how they ultimately decided to vote, and of those voters, 48 percent went for Barack Obama while only 37 percent went for Hillary Clinton. Fourteen percent of those voters voted for John Edwards

Meanwhile, the exit polls also indicate Obama easily beat Clinton among those voters who decided in the last three days - when news reports heavily covered the former president's heightened criticisms of Obama. Twenty percent of South Carolina Democrats made their decision in the last three days and 51 percent of them chose Obama, while only 21 percent picked Clinton.

Bill Clinton's presence on the trail was "very important" to roughly a quarter of those surveyed. Among those voters, Hillary Clinton edged out Barack Obama, 46 to 42 percent.

On Monday, Obama said he felt as if he is running against both Clintons, a charge the New York senator’s campaign said was borne out of frustration. The former president himself later dismissed Obama's comments, saying “I thought he was running against me.”

Campaigning in South Carolina Friday, Obama noted that the Clinton campaign had stepped up its attacks since his Iowa win, and joked that it's good practice for him, so "when I take on those Republicans, I'll be accustomed to it."

- CNN Ticker Producer Alexander Mooney