ABC News' Michael Falcone and Emily Friedman report:

COLUMBIA, S.C. - After Newt Gingrich's decisive win in South Carolina on Saturday, one of Mitt Romney's top strategists sought to sharpen the focus of the race as one between his candidate - a "conservative businessman and a governor" - and Gingrich, "a Congressman from the 90's."

Long-time Romney aide Stuart Stevens previewed the theme the campaign will hammer home as the race enters a new phase - specifically  that Romney brings an outsider's perspective while Gingrich offers nothing more than "solutions from Washington."

"As the only governor, the only person who hasn't been in Washington, I think that makes the whole race a lot clearer," Stevens told reporters after Romney gave his election night remarks in Columbia, S.C. "It's a very, very different race moving on to Florida now."

He said that the departures of Rick Perry and Jon Huntsman from the GOP nominating contest this week has changed the dynamics of the competition.

"Now it sort of gets narrower, it's going to become a two-person, three-person race," Stevens said, noting that Ron Paul does not plan to compete actively in Florida.

"I think it will be a fundamental choice: Do you want to go with somebody who's spent their life in Congress, their achievements in the 90's," he said, "or do you want to pick someone who's been a conservative businessman and a governor? Pretty straight up choice."

He insisted that the campaign was not caught off-guard by their loss in the Palmetto State.

"Well we've always looked at South Carolina - came in fourth last time - as a very, very tough fight. And I think it was a good campaign, I mean it was a campaign about big stuff."

"Nobody runs the table. It was a good campaign, I think, in South Carolina," Stevens added. "It's a great night for Speaker Gingrich, we congratulate him."

(Stevens said Romney called Gingrich from the car on the way to his  speech at the South Carolina state fairgrounds. "They were both laughing, they're big boys they've been here before," he said.)

Romney plans to test some of his campaign's new themes and reinforce some old ones at a major speech the former Massachusetts governor will deliver in Florida on Tuesday. It is meant to be a pre-buttal to President Obama's State of the Union Address that night.

"At the end of this campaign, the speech that he gave when he announced, he can give the next day," Stevens said of Romney.

Two more debates await Romney and his opponents before Floridians head to the polls one week from Tuesday. Looking back, Stevens acknowledged that Gingrich "had a great debate" in South Carolina on Monday night and added that both debates were "great nights for Governor Romney" too.

But when asked whether he regretted the way his candidate handled the issue over the release of his tax returns, Stevens said: "I don't think anything that happened here was about that."