(CNN) — Donald Trump said Wednesday that women who undergo abortions should face “some form of punishment” if the procedure were outlawed.

Trump, who once supported abortion rights, now favors outlawing the procedure, which he called “a very serious problem,” according to excerpts of an MSNBC town hall that is scheduled to air Wednesday evening.

“There has to be some form of punishment,” Trump said in the town hall.

Trump declined to specify how women should be punished if they underwent an illegal abortion.

The Republican front-runner conceded that outlawing the practice would lead some women to seek out abortions illegally.

“Well, you go back to a position like they had where they would perhaps go to illegal places, but we have to ban it,” Trump said during the town hall.

Later Wednesday afternoon, Trump said in a statement released by campaign spokeswoman Hope Hicks that “this issue is unclear and should be put back into the states for determination. Like Ronald Reagan, I am pro-life with exceptions, which I have outlined numerous times.”

In a 1999 interview, Trump called himself “pro-choice in every respect,” though he said that he did not like the concept of abortion.

Widespread condemnation

The town hall comments were met with immediate criticism from progressives.

Democratic presidential front-runner Hillary Clinton retweeted an NBC News reporter, adding, “Just when you thought it couldn’t get worse. Horrific and telling. -H.”

Vermont Sen. Bernie Sanders tweeted, “Your Republican frontrunner, ladies and gentlemen. Shameful.”

Trump’s Republican opponents quickly responded as well.

Ohio Gov. John Kasich told MSNBC, “Of course, women shouldn’t be punished for having an abortion.”

And Brian Phillips, a spokesman for Cruz, tweeted, “Don’t overthink it: Trump doesn’t understand the pro-life position because he’s not pro-life.”

Trump’s comment also drew a swift rebuke from Planned Parenthood’s advocacy arm, which called Trump’s comments “flat-out dangerous.

“Women’s lives are not disposable. There’s nothing else to say, as Donald Trump’s remarks today have said it all,” Executive Vice President of Planned

Parenthood Action Fund Dawn Laguens said in a statement.

CNN’s Noah Gray contributed to this report.