Sen. Kamala Harris (D-Calif.) told a town hall audience in Oakland on Aug. 30, that she plans to co-sponsor the "Medicare for All" bill that Sen. Bernie Sanders (I-Vt.) is introducing in the Senate this fall. (Sen. Kamala Harris)

Sen. Kamala Harris (D-Calif.), a star of the Democrats’ 2016 class who’s seen as a potential presidential candidate in 2020, told an audience in Oakland Wednesday that she would co-sponsor the “Medicare for All” bill that Sen. Bernie Sanders (I-Vt.) is introducing in September.

“It’s just the right thing to do,” Harris said at the end of a town hall meeting, after a standing ovation. “It is so much better that people have meaningful access to health care, from birth through the rest of their lives. The alternative is that we, as taxpayers, are spending huge amounts of money to send them to emergency rooms.”

Within hours, Sanders and Harris were exchanging compliments on Twitter, celebrating the unexpected kick-off of a bill that is still being finished.

Harris’s endorsement was not an enormous surprise. Elected by a landslide last November — the collapse of California’s GOP put her in a runoff with former Democratic congresswoman Loretta Sanchez — Harris had advocated for universal health care during the seven-month Affordable Care Act repeal fight.

But the gusto with which Harris endorsed the bill — “I’m going to break some news,” she said in Oakland — demonstrated Sanders’s inside-outside strategy for legislation that has no chance of passage unless Democrats win back Congress. Privately, Sanders and his circle expect a single-digit number of endorsements for the Medicare for All bill. Several senators, like Sen. Tammy Baldwin (D-Wis.) and Sen. Jack Reed (D-R.I.), had previously endorsed similar bills as members of Congress. Others, facing tough reelection races, may dodge the Sanders bill but endorse some expansion of health-care coverage, under pressure from constituents and activists.

The support of potential 2020 candidates will be most telling. Sens. Elizabeth Warren (D-Mass.) and Kirsten Gillibrand (D-N.Y.) have previously endorsed the idea of single-payer health care; it would be difficult, Sanders said in an interview, for any Democrat to win the 2020 presidential nomination without backing some form of Medicare for All.

Sanders is expected to release the bill on Sept. 13.