White House hopeful Sen. Elizabeth Warren (D-Mass.) fired back at former Vice President Joe Biden over his criticism of her newly released "Medicare for All" plan after her 2020 rival blasted her over the plan's cost.

"The cost projections that we have on Medicare were authenticated by President Obama's head of Medicare. Our revenue projections were authenticated by President Obama's labor economist. And the employer contribution is already part of the Affordable Care Act that President Obama put into the Affordable Care Act," Warren told reporters Friday. "So if Joe Biden doesn't like that, I'm just not sure where he's going."

Warren on Friday released a plan for how to pay for Medicare for All that would not include any direct tax increases on the middle class. Warren has been under pressure from rivals, including Biden, to explain how she would cover the large cost of her plan.

Biden slammed the plan, saying that the plan's proposed $9 trillion tax on employers would be passed off to companies' employees.

"For months, Elizabeth Warren has refused to say if her health care plan would raise taxes on the middle class, and now we know why: because it does," said Biden deputy campaign manager Kate Bedingfield. "Senator Warren would place a new tax of nearly $9 trillion that will fall on American workers."

Several other 2020 candidates also panned the proposal, largely over its cost.

"Democrats are not going to win by repeating Republican talking points and by dusting off the points of view of the giant insurance companies and the giant drug companies who don't want to see any change in the law that will bite into their profits," Warren fired back.

"But if anyone wants to defend keeping those high profits for insurance companies and those high profits for drug companies and not making the top 1 percent pay a fair share in taxes and not making corporations pay a fair share in taxes, then I think they're running in the wrong presidential primary," she added.

Raising taxes on wealthy Americans has been one of the few unifying issues in the 2020 primary field, and nearly all the contenders have said they intend to do so.

Health care has emerged as one of the most divisive issues in the primary, with progressives like Warren and Sen. Bernie Sanders (I-Vt.) advocating for a single-payer system while moderates champion expanding the Affordable Care Act, also known as ObamaCare.