Harris performs better among California Democratic voters who said they were paying the most attention to the campaign (28%), versus those who were paying some attention (22%) or little or no attention (16%).
Sanders's pledge underscores his desire to expand the debate over health care beyond the competing policy proposals and shows how his campaign is seizing on health care as an effective issue to wield against the more centrist Biden - a fight Biden appears to welcome.
Colorado Sen. Michael Bennet, who's pushed a public option on Capitol Hill already, urged Sanders, Harris and Sen.
Biden's health care proposal is anchored by a "Medicare-like" plan that any American, including the 150 million-plus Americans now covered by job-based insurance, could buy on Affordable Care Act exchanges.
Bernie Sanders joked a few hours after Tuesday's broadcast that he might challenge the president to a mile-long footrace.
Some Democratic presidential hopefuls echo Biden's approach, with a handful of them sounding alarms about moving too far left and allowing Republicans to reclaim the health care advantage Democrats enjoyed in the 2018 midterms.
The Washington Examiner's Phillip Klein called Biden's plan "Obamacare on steroids", determining that it would "dramatically increase the price tag of Obamacare and likely erode employer insurance".
"Biden's plan would preserve a broken system", read the campaign's graphic.
The Vilsacks did not formally endorse Biden's campaign for president. CNN asked the state's Democrats who they believe is the most progressive, and 40 percent chose Sanders, compared with just 23 percent for Warren.
Given Biden's role in the passage of Obamacare, it would be hard for him to simply run against it because to do so would be to admit that the most prominent initiative of the Obama administration-sorry, the "Obama-Biden administration"-was a failure".
Though Biden's battle with Sanders may seem to be over the legacy of Obamacare specifically, and of the Obama-Biden administration more generally, it is also a struggle for the heart and soul of the Democratic Party going forward.
Other Democratic candidates have also accepted contributions from industry officials or lobbyists.
"Medicare is a popular, well established program", he said.
The proposal would make existing subsidies more generous and make more middle-income households eligible for them, lowering their out-of-pocket costs.
Biden, a two-term vice president under Barack Obama, said that Trump's behavior is harming the United States in the eyes of other countries. Elizabeth Warren (D-Mass.), perhaps Sanders's most direct rival for the party's liberal voters, has eschewed big-donor fundraising events. Minnesota Sen. Amy Klobuchar and Hawaii Congresswoman Tulsi Gabbard didn't register, falling from 2 percent and 1 percent, respectively. She didn't single Biden out by name, but she said whoever the nominee is, he or she has to energize the Democratic base, specifically young voters and minorities.
"I think it is a beginning and the way you start and the way you move to universal health care", she said in the first debate.