In a forceful push to get Maryland’s public schools reopened, Gov. Larry Hogan and State Superintendent Karen Salmon called Thursday for immediate efforts to return students to classrooms, at least part time, no later than March 1.

The state leaders cited health metrics that have begun to show improvement and research showing that schools are not virus “super­spreaders,” while making the case that the academic and psychological toll of virtual schooling is too great — and that it falls hardest on Maryland’s most vulnerable students.

Hogan (R) said that while the state cannot order school boards to move to in-person learning, it will be taking a firm approach.

“Our children simply cannot afford any more endless roadblocks or any more moving of the goal posts,” Hogan said at a news briefing. “The time has come to get all of our kids back into the classrooms and to reopen our schools.”

He and Salmon are pressing the state’s 24 school systems to switch to a hybrid learning approach, combining in-person instruction with online lessons, by March — a move that would require widespread changes.

Ten school systems are providing in-person learning for “very small” groups of students, while one, in Carroll County, is offering hybrid learning for all students, Salmon said at a hearing earlier in the week.

The state’s two largest school systems, in Montgomery and Prince George’s counties, have had only online instruction since closing schools last March.

Hogan said he wanted to make it clear to teachers unions that “we fully expect teachers to make every effort to return to classrooms.”

He cited the tactics used in other cities and states to press teachers to return, saying Chicago cut off pay for teachers who refused and South Carolina threatened to take away teaching licenses.

Ohio, he said, is offering vaccines to teachers only in school systems that commit to in-person learning.

“We do not want to have to take such actions here in Maryland,” he said. “But if school systems do not immediately begin a good-faith effort to return to the classrooms, we will explore every legal avenue at our disposal.”

Before cases surged in the fall, a majority of Maryland school systems had undertaken some form of in-person learning. Hogan and Salmon have repeatedly pushed districts in that direction. But the surge in cases left many returning to teaching remotely.

The call from state officials comes three days after K-12 teachers became eligible to be vaccinated for the coronavirus, although the rollout of the inoculation program has been spotty statewide.

Hogan and Salmon appeared at a news briefing with Jinlene Chan, acting deputy secretary of the Maryland Department of Health. They cited a range of studies and supporters of reopening schools, including President Biden.

New state reopening guidance was released, with a heavy focus on hybrid learning or daily in-person learning. Distancing, masking and cleaning are still critical, officials said. Chan said that vaccinations should not drive choices about bringing students back for in-person learning. “School reopening decisions should not be based on the availability of vaccination or the level of vaccination,” she said.

Not everyone embraced the call by state leaders.

Montgomery County officials questioned the sudden shift in benchmarks for bringing children back to campus. “We are deeply concerned by the abrupt change to the health metrics guidance set forth by the state given that we are in the height of the pandemic,” school officials wrote in a message to the community.

They said they would need time to “thoughtfully assess these important developments” and would continue to collaborate with state and county health officials. “Our focus remains on the academic needs and the health and safety of our students and staff,” they said.

Monica Goldson, the chief executive of Prince George’s County’s public schools, said in a statement that the school system “continues to assess teaching and learning options as we work towards returning small groups of students to school buildings this spring.”

“We appreciate the patience and flexibility that our students, staff and families have shown throughout this pandemic,” she said. “Their health and safety continue to remain our highest priority.”

Cheryl Bost, president of the Maryland State Education Association, representing more than 75,000 educators statewide, said its members were surprised by the announcement, which she and others found threatening.

Educators have been working “extremely hard” since the pandemic began, she said, and school systems have made decisions based on health metrics.

“Setting an arbitrary date makes no sense,” she said.

Erin Cox contributed to this report.