Presidential candidate Bernie SandersBernie SandersTrump: Hillary Clinton colluded with Democrats to defeat Bernie Sanders Sanders: GOP healthcare bill is a 'moral outrage' GOP at decisive moment on Planned Parenthood MORE repeated Sunday that Bill ClintonBill ClintonBill Clinton: 'The water is going to keep rising’ whether US stays in Paris or not Bill Clinton issues warning on opioid crisis: ‘It’s going to eat us all alive’ Poll: Former AG Lynch should be investigated MORE’s past marital infidelities are “deplorable” but indicated he isn’t interested in talking about them.

“That question annoys me,” Sanders said at the Democratic debate in South Carolina when asked whether he regretted calling the former president's actions “totally disgraceful and unacceptable.”

“I cannot walk down the street — Secretary Clinton knows this — without being told how much I have to attack Secretary Clinton,” Sanders said of his rival for the party's nomination, former Secretary of State Hillary ClintonHillary Rodham ClintonTrump: Hillary Clinton colluded with Democrats to defeat Bernie Sanders The Memo: GOP pushes Trump to curb Mueller attacks Trump: 'Why no action' from Obama on Russian meddling? MORE.

After Sanders made the comment, Clinton adviser John Podesta attacked him. The senator on Sunday insisted he would not engage in negative campaigning against Hillary Clinton.

“I have avoided doing that, trying to run an issue-oriented campaign,” he said to huge applause from the audience. 

Asked by NBC reporter Andrea Mitchell why he answered the question, Sanders said: “I was asked a question. Then if I don't answer, then it's another front-page story.

“Yes, his behavior was deplorable,” Sanders continued. “But I'm going to debate Secretary Clinton and Gov. [Martin] O'Malley on the issues facing the American people” and not on Bill Clinton's personal life.

Republican front-runner Donald Trump has repeatedly used the former president's sex scandals as lines of attack, calling him “one of the great woman abusers of all time.”

The real estate mogul has defended his remarks, saying Bill Clinton is fair game after Hillary Clinton accused Trump of having a “penchant for sexism.”