There was good reason why so many state Senate Democrats flipped at the last minute to advance a $400 billion single-payer health care bill without a clue of how to pay for it — the wrath of “Berniecrats.”

“It was amazing — I’ve never seen so many votes turn so fast,” said one state senator who attended the the closed-door Democratic caucus that preceded the 23-14 vote Thursday night.

The senator, who asked not to be named because caucus meetings are off the record, said Democrats felt that saying “no” — or even holding off on a vote until the finances were laid out — was not worth crossing the politically powerful California Nurses Association and other single-payer advocates who supported Bernie Sanders for president.

“They were threatening members that if they did not vote for the bill, they would run someone against them in the next primary,” the senator said.

Nurses union spokesman Chuck Idelson said he did not know of any threats, but that “there was a very active grassroots campaign that included phone banks, town hall meetings, rallies and people going door to door in districts.”

“People expect the lawmakers to represent them — not corporate interests and insurance companies,” Idelson said.

One of those targeted was state Sen. Steve Glazer of Orinda — the lone Democrat to vote “no” on the single-payer bill, saying it wasn’t “a fully baked plan and had no funding proposal.”

Glazer wanted to have the costs fleshed out, and then he wanted the whole plan put to a vote of the people.

As for being targeted as a corporate lackey?

“It’s a free country,” Glazer said. “They should remember our goals are the same and it’s a matter of how we get there.”

The plan now goes to the state Assembly.

On your marks: The 2018 race for lieutenant governor now includes two former Obama administration envoys.

Jeff Bleich, an East Bay attorney and former ambassador to Australia, kicked off his campaign last week in Oakland. He joins Sacramento businesswoman and former Ambassador to Hungry Eleni Kounalakis — along with Los Angeles physician Asif Mahmood and state Sen. Ed Hernandez of West Covina (Los Angeles County) — in the 2018 Democratic derby to replace Lt. Gov. Gavin Newsom. No Republicans have yet entered the race.

Bleich was a special counsel to Obama in the White House before he was appointed ambassador to Australia in 2009. He held that post for more than four years before returning to private law as a cybersecurity and public policy expert.

As for how he intends to compete in such a crowded field?

“I have such good hair,” cracked Bleich, whose receding hairline stands in stark contrast to Newsom’s jelled locks.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or email matierandross@sfchronicle.com. Twitter: @matierandross