Republican presidential candidate Donald Trump (left) leads rivals Ted Cruz (center) and John Kasich as they take the stage for the Republican presidential candidates debate in Detroit, March 3, 2016. Reuters/Jim Young

Republican front-runner Donald Trump appeared to brag about his penis size during the GOP debate Thursday night. After the moderators asked Florida Sen. Marco Rubio about his attacks on Trump, the New York businessman responded by saying that he took issue with Rubio’s criticism of his hand size.

“I also have called him a lightweight ... and I have to take that back,” Trump said.

He added that Rubio “hit me on my hands,” referring to Rubio’s criticism that Trump was a “short-fingered vulgarian.”

Trump held up his hands and said, “Look at my hands. Are they small?” He then said Rubio implied if his hands were small, “then something else must be small. I guarantee you there’s no problem,” Trump said.

For Rubio’s part, he responded to the moderator’s question by arguing that Trump deserved the attacks.

“Donald Trump has basically mocked everybody with personal attacks,” Rubio said. “If there’s anybody that ever deserved to be attacked that way, it’s Donald Trump.”

Donald Trump Presidential Candidate Profile | InsideGov

Thursday’s debate came at a critical point in the race for Trump and his rivals. After sweeping victories on Super Tuesday this week, the New York billionaire racked up enough delegates to be well on his way to the Republican presidential nomination. However, his success triggered a barrage of new attacks from members of the GOP establishment who still hope to stop a Trump candidacy.

On Super Tuesday, an anti-Trump super PAC hired former Jeb Bush spokesman Tim Miller and signaled it was getting ready to spend heavily in an attempt to stop Trump in primaries later this month. Then former presidential candidate Mitt Romney stepped up to the plate, delivering a blistering speech Thursday at the University of Utah, in which he trashed Trump’s business record, called him a “phony” and a “fraud” and implored fellow Republicans to choose anyone but the real estate mogul.

Trump responded in kind, mocking Romney’s loss in the 2012 presidential campaign and his efforts to get Trump’s endorsement during that cycle. As is his signature, Trump also tweeted insults about the former governor of Massachusetts before Romney began his speech Thursday.

The debate also marked Trump’s rematch with Fox News host Megyn Kelly, who was one of the moderators Thursday night. The two have not spoken since their showdown at the first GOP debate last August, when Trump said Kelly treated him unfairly after she challenged him on his previous treatment of women.