"I think it's a terrible plan," he said.
"The single-payer, Medicare-for-all bill that these people are all getting behind is a terrible health care policy and it's terrible politics. I believe we will lose the election if we put up a nominee who runs on this.
"We have kind of mindlessly been following Senator Sanders - who's not even a Democrat by the way - on this issue."
He added he believed Sen. Elizabeth Warren, D-Mass., "outsourced" her health care platform to Sanders.
The former lawmaker claimed his more moderate plan to provide health care coverage to all Americans was something voters could get behind.
"I think they saw me as someone who is pragmatic and practical and uses common sense and tries to solve problems," he said.
"That's been the theme of my campaign from the beginning.
"Someone has to stand up and talk about it because I can assure you if we put a nominee of who runs on this, Donald Trump is going to talk about it. He's never going to shut up about it."
During Wednesday's debate, Delaney scolded his rivals by saying they “should be the party that keeps what’s working and fixes what’s broken.”
He continued, “We’re supporting a bill that would have every hospital close.”