Attacks on Romney getting personal

Romney's conscious of the criticism. Outside an Iowa HyVee, a day after he compared Obama to the French queen Marie Antoinette, Romney was asked if he could say, "let them eat cake" in French.

"I can, but I won't," Romney replied.

Santorum, the former Pennsylvania senator, rolled out a fundraising email Friday that warned his supporters that picking Romney would be like picking failed nominees John McCain, Al Gore, Bob Dole and even Dukakis, another former Massachusetts governor.

"Americans have been down this road before," Santorum says in the appeal. "At various times both parties nominated boring candidates because they were considered 'electable.' In every one of those cases, they weren't electable at all. Now Republicans are again thinking about nominating another bland and boring candidate for president — Mitt Romney."

Santorum compared Romney to Obama, who has had a reputation for being standoffish, saying: "Republicans can't afford a nominee" who resembles "Obama so much that he can't barely be distinguished from him."

Santorum also has hit Romney for appearing distant, calling his rival "someone who, I think, has had a difficult time relating to the type of voters we're going to need if we're going to win this election."

He cast Romney's tenure at the helm of a venture capital firm in terms that may resonate with many American workers: "It doesn't necessarily mean that you want your boss running for president, right?"

So far, Romney hasn't faltered as he answers attacks on his record. Will he when it gets personal?