(CNN) Vermont Sen. Bernie Sanders on Tuesday night sought to fully divorce himself from supporters who have harassed others online and questioned whether anyone who believes in his agenda would attack a union leader.

Top officials at the Culinary Union in Nevada accused Sanders supporters of swarming them online after the union distributed fliers that said Sanders would "end" their health care.

Sanders at a CNN town hall questioned whether some of the social media comments cited by critics were, in fact, written by his supporters.

"The idea that anybody who works with me would make a vicious attack against a union leader just because we disagree on an issue is incomprehensible to me," Sanders said. "And you know what, I'm just not sure that that's true."

He also pointed out that members of his own staff had been the targets of online harassment.

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