They’re fighting for many of the same progressive ideas and, one assumes, many of the same voters in the Democratic primary. But Sens. Bernie Sanders and Elizabeth Warren have studiously avoided attacking each other, even as polls show them neck and neck at the top of the Democratic primary race.

Sanders, for one, wants to keep it that way. Asked if he’s going to criticize Warren on policy differences, Sanders said, “That’s not what I do.”

In an interview airing Wednesday night on "VICE News Tonight on HBO," Sanders said he’s not interested in getting into a mud fight with Warren, even as the primary gets tighter.

Sanders — who was aggressive in his criticism of Secretary of State Hillary Clinton’s platform in the 2016 primary race — said that directly comparing his policy plans to Warren’s “is not the way you necessarily win a campaign.”

“The way you win a campaign is to let people know what you stand for, what I stand for,” he said.

Asked why a voter should choose him over Warren, Sanders said, “Well, that's a decision that someone is going to have to make.”

He did say, however, that he’s been advocating for these issues longer than Warren has.

“I would suggest in my defense that I've been doing this for, as you indicated a few moments ago —check me out, and people may find me a little bit boring and repetitious — but I have been fighting these fights for about 30 years.”

Watch the full segment on VICE News Tonight on HBO on Wednesday at 7:30 p.m.