Vermont Sen. Bernie Sanders sought to differentiate himself from his 2020 rival Sen. Elizabeth Warren, D-Mass., by taking aim at her progressive bonafides during an interview that aired Sunday.

Sanders, a self-proclaimed democratic socialist, told ABC's "This Week" that he is the more progressive candidate in the race compared to Warren, who he noted once described herself as a "capitalist to my bones." He added that they have a "somewhat" but "not quite" the same policy outlook.

"[E]lizabeth Warren has been a friend of mine for some 25 years," Sanders said. "And I think she is a very, very good senator. But there are differences between Elizabeth and myself. Elizabeth I think, as you know, has said that she is a capitalist through her bones. I’m not. I think the situation today that we face in this country of the greed and the corruption that is existing in Washington, that is existing at the corporate elite level ... I am, I believe, the only candidate who’s gonna say to the ruling class of this country, the corporate elite, enough, enough with your greed and with your corruption. We need real change in this country."

Warren, who has surged in recent Democratic primary polling, in 2018 reportedly called herself a "capitalist to my bones" in describing her approach to policy. Sanders, who is trailing Warren in those polls, sought to cast himself as the candidate farthest to the left among the 2020 field having authored the "Medicare for All" legislation that other candidates including Warren have endorsed.

"I mean, Elizabeth considers herself, if I got the quote correctly, to be a capitalist to her bones," Sanders said on Sunday. "I don’t. And the reason I am not is because I will not tolerate for one second the kind of greed and corruption and income and wealth inequality and so much suffering that is going on in this country today, which is unnecessary."

The two are set to face off Tuesday at a jammed-packed Democratic primary debate in Ohio. Earlier this month, Sanders suffered a heart attack and subsequently left the campaign trail to recover. He has pledged to continue campaigning and said he will participate in the Tuesday debate.