Sen. Bernie SandersBernard (Bernie) SandersClinton backs Georgia governor hopeful on eve of primary The Hill's 12:30 Report — Sponsored by Delta Air Lines — Frenzy over Kennedy retirement rumors | Trump challenges DOJ Bernie Sanders announces Senate reelection bid MORE (I-Vt.) denies that his presidential campaign has taken its gloves off against Democratic front-runner Hillary ClintonHillary Diane Rodham ClintonClinton backs Georgia governor hopeful on eve of primary Pressure rising on GOP after Trump–DOJ fight’s latest turn Press: Why Trump should thank FBI MORE.

“When they talk about me running a negative campaign, that’s just absurd,” he said Monday on ABC’s “Good Morning America."

“I have tried my best to run a positive, issue-oriented campaign by never making personal attacks against Hillary Clinton while debating the issues,” he continued. "I’ve never run in my entire political life a negative ad. Not too many people can say that.”

Sanders then mocked Clinton’s senior campaign strategist Joel Benenson for suggesting last week that his campaign is the “most negative” in Democratic primary history.

“Ever?” Sanders asked while chuckling. "My God! Going back 500 years.”

Sanders also predicted he would defeat Clinton in Iowa’s caucuses Monday evening by attracting first-time participants.

“I think we will win if there is a large voter turnout,” he said. "I think if a lot of non-traditional voters – younger people, working people, low-income people – participate in the political process and come out in big numbers, I think we will win.”

Sanders added that the hardest part of seeking the Oval Office is meeting his supporters’ expectations.

“It’s a very humbling and scary experience,” he said. "People are putting so much faith into you that you don’t want to let them down. It’s difficult.”

Clinton and Sanders have sharpened their rhetoric as the gap in voter support between them closes. Sanders trails  the former secretary of State by 4 points on average heading into Iowa’s first-in-the-nation caucuses.

The self-described Democratic socialist has long argued he is just as electable as Clinton despite his political outsider status.