Mitt Romney, addressing for the first time the negative attacks on him by the Democratic National Committee and fellow GOP presidential contenders, pushed back on Tuesday against accusations that he is a “flip-flopper” on the issues.

The healthcare issue is “by far the biggest challenge I have in the primary race,” Romney said on Fox News’ “Special Report” with Bret Baier. “If I were willing to say anything to get elected, wouldn't I just say, oh, it was a mistake.”

Romney slammed his GOP rivals for brushing aside past actions as “mistakes” and reiterated that he stands by the healthcare legislation he implemented as governor of Massachusetts. Many conservatives have attacked him on the bill’s similarities to President Obama’s healthcare plan, particularly its inclusion of an individual mandate.

“If it keeps me from winning a primary, so be it,” Romney said.

He also said he is the candidate best equipped to challenge Obama on the topic due to his experience with the issue.

He took a jab at Newt Gingrich, who is currently leading Romney in the polls in several key early states, calling him a “good man” but pointing out he spent several decades in Washington.

“He spent his last 30 or 40 years in Washington. I spent my career in the private sector,” said Romney, who has emphasized his private business experience in comparison to the “career politicians” in Washington. “I think to get President Obama out of office, you're going to have to bring something to the race that's different than what he brings. [Obama is] a lifelong politician.”

Romney also sought to distance himself from Gingrich on the topic of illegal immigration. Gingrich, who has categorically opposed the policy of amnesty, recently argued that some families of illegal immigrants should be allowed to stay in the United States.

“If he's going to do what I believe he said he was going to do for those people who would be allowed to stay permanently and become citizens, that would be providing for them a form of amnesty,” Romney said. “My view is pretty straightforward. For those people who have come here illegally, they should have the opportunity to get in line with everybody else who wants to come into this country, but they go to the back of the line and they should be given no special pathway to citizenship or permanent residency merely because they've come here illegally. Whether they apply here or whether they apply by going home, I think I've said in the past, I think it makes more sense for them to go home if we set up a system for them to apply here.”

The DNC has slammed Romney for changing his position on numerous issues, including healthcare, abortion, climate change, and immigration. According to Romney, the only issue he “changed my mind” on in the past is that of abortion, shifting more pro-life during his time as governor.

“Bring it on, we’re ready for them,” Romney said of the recent ads released by the DNC on Tuesday, according to ABC News.