Sens. Bernie Sanders and Elizabeth Warren may not have been onstage, but their presence loomed large as the ten candidates for CNN's second Democratic primary debate fought over healthcare under the parameters set by the two progressive front-runners. 

Sen. Kamala Harris (D-Calif.) was on the defensive for most of the first portion of the night due to her version of "Medicare for All" which involves a ten-year phase in for the program.

"The cost of doing nothing is far too expensive," said Harris. "We must act."

Harris also called back to Tuesday night's criticisms of more right wing Democrats from Warren and Sanders.

Among her critics was former Vice President Joe Biden, who is running largely on a platform of expanding the Obama-era Affordable Care Act (ACA), saying that his plan "builds on Obamacare."

But, as journalist Andrew Bard Epstein pointed out to Common Dreams, for all of Biden's posturing, the ACA isn't exactly the  gold standard. 

"I keep saying this but the fact that healthcare remains the major issue of the Democratic primary, and for many voters, is a tacit admission of Obamacare's failure, or what Biden called a 'big fucking deal' because he thought the issue was now solved," said Epstein. "Does it feel solved to you?"

As Splinter reporter Libby Watson noted, Biden doesn't appear to have a firm grasp on the subject in general. 

"Biden does not understand healthcare," tweeted Watson.

Ultimately, of course, the candidates onstage were debating within the frame set by Sanders and Warren, who spent the first night arguing with their opponents on the moral case for universal healthcare. 

That connection was remarked upon by observers Wednesday night. 

The New York Times' Jamelle Bouie called that portion of the debate for the real winners.

"The winners of this health care debate are Bernie Sanders and Elizabeth Warren," said Bouie.