"If I had a thought when I was 18, does that mean I'm married to it for the rest of my life?" Priebus asked.
Preibus went on to criticize the ad as "a joke," noting that the DNC has only spent $14,000 on the buy.
"I just don't think having a person forced to be married to positions that they've taken and then altering them since they learned new information ... is something that ought to be condemned," Preibus said.
The DNC and Obama campaign have almost exclusively targeted presidential candidate Romney for criticism among the Republican field, launching a website called 'WhichMitt.com' and complementary YouTube channel, both playing off Romney's equivocations on policy issues.
"The core principle that drives Mitt Romney [is] getting elected," said Jim Messina, President Obama's top campaign official, last month.
But Preibus said that it was important for Republicans to target liberal states with candidates like Romney, Massachusetts Sen. Scott Brown, and New Jersey Governor Chris Christie, who could attract moderates and independents.
"I think winning in blue states ... I think its something our party needs to build on and do better at," Preibus said.