Image Credit: ABC

CEDAR RAPIDS, Iowa - Mitt Romney today said he believes that Newt Gingrich, with "no question in my mind," would be the easier candidate for President Obama to beat in the general election, hinting that he and the former House speaker would bump heads at Saturday night's debate to define their differences.

In an exclusive sit-down interview with ABC News anchor David Muir this afternoon in Cedar Rapids, Iowa, Romney shied away from attacking Gingrich outright but suggested that a more pointed exchange between him and Gingrich will happen as soon as the next debate.

"Well, we'll be talking about issues, of course, and we have differing views on some issues and we'll be talking about those differences," he said. "That's, after all, the nature of a debate."

Pressed on whether he'd be willing to mix it up with Gingrich on stage, Romney didn't explicitly rule it out.

"I'd expect Newt Gingrich and I will have some differences and we'll be able to discuss those as well," Romney said.

After 24 hours of scathing attacks directed at Gingrich from Romney surrogates, with several people associated with the campaign using words such as "untrustworthy" and "unreliable" to describe Gingrich, Romney was asked whether he, too, believes Gingrich is untrustworthy.

"Well [there are] a lot of people that worked with Speaker Gingrich in the past and they're going to say whatever they will," Romney said. "Heaven knows I can't write a script for all the people that support me."

Questioned specifically about the television ad, "Leader," which touts Romney's family values, the candidate told ABC News that the ad was not intended to be a veiled swipe at Gingrich.

"Actually, in each of my campaigns, I've begun advertising season with an ad about me and my family and my values," he said.

"There was no attempt to in any way to implicate anybody else in that," he said. "I'm just trying to let people know who I am."

As for whether Gingrich's personal life - specifically his three marriages - should be considered a liability, Romney said he would "not give advice to the American people as to what they should look when they decide who should be their nominee or their president."

"I'm not going to tell them which things they're allowed to consider," Romney said, "and which things they're not."