The California Nurses Association, the liberal labor powerhouse that sent thousands of volunteers across the country in support of Bernie Sanders’ presidential primary run, appears to be sitting out the race between Hillary Clinton and Donald Trump.

“Our position is still under consideration,” said union spokesman Chuck Idelson — though he added, “We know that nurses are not going to vote for Trump.”

On the other hand, union President RoseAnn DeMoro did rake Clinton campaign chairman John Podesta in a Twitter blast last week for a WikiLeaks email showing “Clinton camp trying to get press to attack #Nurses supporting Bernie. Never happened in Obama era.”

The nurses union’s problem with Clinton appears to be her unwillingness to support single-payer health care coverage. Sanders, on the other hand, embraced the single-payer plan.

It’s not the first time the union has declined to back the Democratic presidential nominee.

In the 2000 election, the nurses backed Green Party candidate Ralph Nader — whom some still blame for draining off votes from Al Gore in Florida and handing the presidency to George W. Bush.

“Yes, CNA endorsed Nader in 2000,” Idelson said. “He embodies the same values our nurses do: single-payer health care — and boy do we need that now — curbing the enormous power of Wall Street and corporate America over the lives of working people, economic justice, a humane foreign policy, and so much more.”

“In fact,” Idelson added, “the same policies and issues Bernie articulated so well in his campaign.”

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