While admitting his controversial comments last week on women and abortion -- and the subsequent back-tracking -- may have taken a toll on his campaign going into Tuesday’s Wisconsin primary, Republican presidential front-runner Donald Trump also took to the airwaves Sunday to defend equally controversial statements that NATO was “obsolete” and that South Korea and Japan “would be better off” if they had nuclear weapons.

In recent days, the first-time candidate retweeted an unflattering picture of primary rival Texas Sen. Ted Cruz’s wife and suggested NATO is obsolete and “some form of punishment” is needed for women who have abortions if the procedure were illegal.

“I could have done without the tweet,” Trump told “Fox News Sunday.”

Trump wouldn’t agree that he made a mistake on the abortion question, but said, “As a hypothetical question, I would have rather answered it in a different manner.”

He eventually issued two statements to clarify his comments.

Those mistakes appear to be hurting him in Wisconsin, which holds its primary on Tuesday, and with women voters, a key voting bloc in the general election.

Most polls show Trump trailing Cruz in Wisconsin, after leading him by double-digits in late February. And a recent WSJ/NBC poll shows 70 percent of women have an unfavorable view of him.

However, Trump on Sunday held firm on his position that NATO has become obsolete.

He said the international peacekeeping force doesn’t focus enough on stopping terrorism and that the United States pays too much for what it gets in return.

“It's obsolete,” Trump said. “We're not getting the benefits that we should be getting for the money. We're carrying a lot of countries. … What I said was exactly right. … I think NATO has to be readjusted.”

Trump also stuck by his suggestion that it’s perhaps time for the U.S. to stop paying most of the bill to defend Japan and South Korea against nuclear-armed North Korea, even if that means touching off a nuclear arms race in the Korean peninsula.

“You have Pakistan and you have North Korea. And you have China. And you have Russia. And you have India. And you have the United States and many other countries have nukes,” Trump said. “You already have a nuclear arms race.”

Trump has run his campaign since June in an unabashed style in which he has risen in the polls in part with unapologetic remarks about deporting roughly 11 million illegal immigrants in the United States and a call for a temporary ban on Muslim immigrants.

On Sunday, the New York real estate magnate still expressed confidence about doing well in Wisconsin and winning the party nomination. He acknowledged, however, being a politician for just eight months and having a “learning curve.”

He also remained defiant regarding his decision to defend campaign manager Corey Lewandowski, who has been charged with misdemeanor battery for allegedly grabbing the arm of a female reporter.

Trump said the reporter, Michelle Fields, originally and falsely claimed she was nearly knocked to the ground and that Lewandowski is a “good, honest man.”

“The easier thing would have been: ‘Corey, you're fired. You're not very good at that, OK?’ But I don't want to ruin him . . . I don't want to destroy him,” Trump said.