Barack Obama's frank admissions about use of marijuana and cocaine in his youth could hurt his chances of winning the presidency in a general election against a Republican contender, according to an advisor for rival Hillary Clinton.

CNN reported Dec. 13 that Bill Shaheen, who co-chairs Clinton's campaign in New Hampshire, said that Republicans will "jump on" Obama's admissions should he defeat Clinton in the Democratic primary and become the party's nominee for president.

"The Republicans are not going to give up without a fight … and one of the things they're certainly going to jump on is his drug use," Shaheen said. "It'll be, 'When was the last time? Did you ever give drugs to anyone? Did you sell them to anyone?' ... There are so many openings for Republican dirty tricks. It's hard to overcome."

Obama's campaign slammed Shaheen's comments as "an increasingly desperate effort to slow [Clinton's] slide in the polls."

Clinton's spokesperson, Phil Singer, said Shaheen's comments "were not authorized or condoned by the campaign in any way," and Shaheen later issued a statement in which he expressed regret for the remarks.