Donald Trump claimed during the first presidential debate on Monday night that he considered using sordid details of Hillary Clinton's personal life against her, but refrained.

"I was going to say something extremely rough to Hillary and her family, and I said to myself, I couldn't do it. It's inappropriate. It's not nice. But she's spent hundreds of millions of dollars on negative ads against me, many of which are untrue," Trump said. "It's not a nice thing."

Trump later reiterated to Yahoo News reporter Hunter Walker in the spin room he was indeed tempted to bring up former President Bill Clinton's decades-old extramarital affairs.

"I was, but I decided not to do it out of respect for Chelsea," the Republican presidential candidate said, referring to Chelsea Clinton, the Clintons' daughter.

I asked Trump if he was tempted to bring up Bill Clinton's sex scandals. pic.twitter.com/2xtarFaHzn — Hunter Walker (@hunterw) September 27, 2016

The comments came after the Republican presidential nominee defended his assertion that Hillary Clinton does not have a "presidential look."

Pressed by moderator Lester Holt, Trump doubled down.

"She doesn't have the look. She doesn't have the stamina. I said she doesn't have the stamina," Trump said.

Clinton quickly shot back, touting her experience as secretary of state as proof of her stamina.

"As soon as he travels to 112 countries and negotiates a peace deal, a cease-fire, a release of dissidents, an opening of new opportunities and nations around the world, or even spends 11 hours testifying in front of a congressional committee, he can talk to me about stamina," Clinton said.

"Hillary has experience, but it's bad experience," Trump replied.

Clinton responded by highlighting some of Trump's past comments about prominent women.

"He tried to switch from looks to stamina, but this is a man who called women pigs, slobs, and dogs," Clinton said.

She added: "One of the worst things that he said was at a beauty contest — he loves supporting them and hanging around them — he called this woman Miss Piggy and then he called her Miss Housekeeping, because she was Latina."