(Image Credit: Chip Somodevilla/Getty Images)

ATLANTA - Mitt Romney, asked if there were any lessons learned in the wake of losing all three Republican voting contests Tuesday night, said that he simply "wasn't there to respond" to former Sen. Rick Santorum's attacks in the days leading up to voting.

But today, speaking to reporters on a tarmac in Atlanta, where he flew from Colorado after losses in Minnesota, Missouri and Colorado Tuesday night, he did not hesitate to go on offense, accusing two chief GOP rivals of behaving "like Democrats."

"I think, as with South Carolina, we took a lot of incoming in South Carolina and didn't really respond," he said. "Obviously, Sen. Santorum was able in Minnesota to level a lot of charges, some of them not accurate, and I wasn't there to respond. That was just because I happened to be fighting hard out in Nevada. But I will clearly make the differences between myself and my opponents very clear in where I think they have misrepresented my record and my views, and I'll make that very clear."

Romney's tarmac comments were his first media availability since Feb. 1.

"I think a lot of us feel that the Republican Party lost its way in the past," he said. "We spent too much, borrowed too much, earmarked too much. I'm talking about we in the general sense because these were folks in Washington. And, frankly, Rick Santorum and Newt Gingrich were a big part of the 'we' that spent too much, borrowed too much and earmarked too much."

Romney has barely mentioned Gingrich or Santorum by name since his win in the Florida primary, pivoting his attention to focus on President Obama. Today, Romney hit the GOP field head on, lodging fresh attacks on both candidates, a change in strategy that one of his senior advisors predicted following Tuesday night's losses.

"Under Newt Gingrich earmarks doubled," said Romney. "Rick Santorum was a major earmarker and continues to defend earmarks. Under Rick Santorum, he voted to raise the debt ceiling, I believe, five different times to a tune of about an addition $3.5 trillion. I believe that while Sen. Santorum was serving in Congress and the Senate, government spending increased by some 80 percent. Republicans spent too much money, borrowed too much money, earmarked too much, and Rick Santorum and Newt Gingrich have to be held accountable."

Romney suggested that Santorum and Gingrich could be considered part of the reason the tea party movement began.

"One of the reasons the Tea Party grew up, of course, is that people were unhappy about incumbents, people who had spent their careers in Washington borrowing, spending and earmarking," said Romney. "And they said, 'Look, we want to throw the guys out that have been there too long and bring in some new faces. And in this race, I'm the only guy that hasn't spent time in Washington. And Sen. Santorum and Speaker Gingrich, they are the very Republicans who acted like Democrats.

"When Republicans act like Democrats, they lose," said Romney. "And in Newt Gingrich's case, he had to resign. In Rick Santorum's case, he lost by the biggest margin of any Senate incumbent since 1980."

"Again, borrowing, spending and earmarking is not a good combination if you're a Republican and not a good combination, in my view, for America," he said.

Following Tuesday night's losses, Romney said he always expected a "long process" to get the Republican presidential nomination.

"As you've heard me say over some months now, Sen. McCain, you know, after, I think, winning Florida, he went on to lose - I don't know - 17 or 18 contests after that, but was able to put the delegates together by focusing on the process of gathering delegates, as we will," said Romney.

Romney's campaign made that same argument regarding McCain's campaign early Tuesday, in an apparent attempt to tamp down expectations.

"There are big states coming up with a lot of delegates," Romney said today. "We'll compete actively there. As you know, we didn't devote a lot of money and time to the states yesterday. We were spending our time and money in Florida and Nevada.

"Sen. Santorum took a different course, left Florida, left Nevada, went to the other states and he was able to reap the rewards of that approach," Romney added. "There will certainly be places where he wins, and there will be places where I win."

"There's no such thing as coronations in presidential politics," Romney said. "It's meant to be a long process. It's not easy to get the nomination, it's not easy to be elected president."