SAN FRANCISCO (AP) — An effort to reopen California schools is foundering, stoking frustrations across America’s most populous state from parents eager to get their children back in classrooms and a governor who wants them there.

Parents and behavioral experts say many schoolchildren are feeling helpless or depressed and need a classroom setting to improve their mental health. An exasperated Gov. Gavin Newsom told school officials last week to “pack it up” if they fail to resume in-person classes soon.

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Teacher unions say they won’t send their members into an unsafe environment. They want all teachers vaccinated before returning to the classroom.

While Texas, Florida and New York are among states that have resumed some classroom instruction, California’s 10,000 public schools have for the most part been closed since March. As most of the state’s 6 million public school students approach a one-year anniversary of distance learning, parents are grappling more than ever with the toll of isolation and intense screen time on their kids’ well-being.

The U.S. Centers for Disease Control Prevention said in a recent study that schools should resume in-person learning as soon as possible and there is little evidence of spreading the infection when proper precautions are taken, such as masks, physical distancing and proper ventilation.

Newsom has said he will not force public schools to reopen but instead wants to “incentivize” them and has proposed a $2 billion plan that has met criticism from superintendents, unions and lawmakers. Clearly frustrated, Newsom last week implored them to find a solution to reopen.

“If we wait for the perfect, we might as well just pack it up,” Newsom said during a video meeting of the Association of California School Administrators.

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The plan Newsom unveiled Dec. 30 would give schools extra funding for COVID-19 testing and other safety measures if they reopen. Elementary schools that reopen to their youngest students by mid-February would get more funding than schools that reopen later, and schools that don’t submit an application don’t get to tap the fund.

The proposal, called “Safe Schools for All,” sets no timeline for middle and high schools. The plan set a Feb. 1 deadline for districts to file COVID-19 safety plans to qualify for the funding, but that deadline will pass Monday without the legislative approval needed to start the program.

Newsom told educators in blunt terms that he is willing to negotiate but certain demands, including the call by unions to have all teachers vaccinated before school starts, were unrealistic given the shortage of vaccines.

“If everybody has to be vaccinated, we might as well just tell people the truth: There will be no in-person instruction in the state of California,” Newsom said Thursday.

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The same day, the California Teachers Association sent the governor a letter again criticizing his plan.

“The virus is in charge right now and it does not own a calendar,” the letter said. “We cannot just pick an artificial calendar date and expect to flip a switch on reopening every school for in-person instruction.”

The largest school districts — Los Angeles, San Diego, Fresno, Long Beach, San Francisco and others — say the plan sets unrealistic rules and timelines.

Under the plan, schools are only eligible to reopen once their daily new case rate falls below 25 per 100,000 residents, a level that most of California is far from reaching even though virus rates are dropping fast from precipitous highs.

“We do not need financial incentives to reopen, we need it to be safe,” San Diego Unified School District Board President Richard Barrera said. “The idea that we’re going to be anywhere near 25 is simply not going to happen by mid-February.”

Newsom’s plan requires rigorous COVID-19 testing of students and staff, which schools support but many say they can’t afford.

Austin Beutner, superintendent of the Los Angeles Unified School District that is the second largest in the country, said his city remains an epicenter for the virus and conditions must improve before schools can reopen.

“I’m asked every day by hundreds of teachers, ‘When do you think we can get the vaccine?’ And all I say is, ‘I don’t know,’” said Beutner, noting that it is impractical to negotiate with teachers on a reopening plan that was still under debate in the Legislature and is likely to change.

Many smaller school districts have the same complaints, state Sen. Connie Leyva, chair of the Senate Education Committee, told a recent hearing on the proposal.

“I would like to know that there is actually a school district out there that thinks this plan is workable, because I have not found one,” said Leyva, a Democrat who represents parts of Los Angeles and San Bernardino counties.

Christine Atha, who lives near Sacramento, initially supported distance learning for safety reasons but now wants it to end.

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“These kids don’t need any more videos to watch from behind their desk sitting alone in their rooms. The only thing they need is to return to in-person school,” said Atha, who has two teenagers in high school, both showing signs of depression and anxiety. “The science says you go back to school when it’s time. And it is high time.”