Former Vice President Joe Biden mocked Sen. Bernie Sanders’ (D-VT) trust in corporate America during the third Democrat primary debate on Thursday.

Biden mocked the self-described Democrat socialist over his signature Medicare for All proposal, claiming the plan was not realistic about the costs and projected savings.

“If you notice, nobody’s yet said how much it’s going to cost the taxpayer,” Biden said while lambasting the universal healthcare proposal. “I hear this large savings my friend from Vermont thinks that the employer is going to give back if you negotiate as a union all these years, got a cut in wages because you got insurance.”

The former vice president proceeded to ask Sanders if he believed the employers were goin to “give back that money to the employee.” When the stern faced Sanders responded, “they will,” Biden shot back with a joke about the ideological differences between them.

“Well let me tell you something,” Biden said. “For a socialist, you have a lot more confidence in corporate America than I do.”

Since announcing his presidential campaign in late April, Biden has relentlessly attacked Medicare for All and its proponents for being overly ambitious about the program and its costs.

Instead of signing up to back the Sanders-authored plan, like a majority of the Democrat field, Biden has proposed expanding Obamacare through a public option. Biden’s new “public health insurance option” that will function similarly to Medicare and is estimated to cost more than $750 billion over the first decade of implementation.