American Federation of Teachers President Randi Weingarten said Sunday that she personally supports her members working with school districts to create vaccine mandates, an announcement that represents a significant shift from national teachers’ unions previous hesitance to endorse such requirements.

In a Sunday interview with Meet the Press on NBC, Weingarten said that the spread of the coronavirus Delta variant is “alarming” and led her to reconsider the issue of vaccine mandates recently. She indicated that she plans to bring together the union’s leadership this week to discuss the AFT’s position about the issue.

“As a matter of personal conscience, we need to be working with our employers—not opposing them—on vaccine mandates,” Weingarten told Meet the Press host Chuck Todd on NBC.

Weingarten, who represents 1.7 million members, later told Todd that “we are probably the most vaccinated profession right now” and that her members have largely gotten vaccinated already. “It’s not a new thing to have immunizations in schools,” she said.

Yet she also noted that medical and religious exemptions should be part of discussions about vaccine mandates.

National teachers’ unions have been reluctant to endorse a vaccination mandate. But over the past week, Weingarten sent strong signals that her position might change, again citing the Delta variant and the likely full approval of the vaccines by the Food and Drug Administration in the not-too-distant future.

National Education Association President Becky Pringle has also recently called for everyone who can be vaccinated to get vaccinated. But she has stopped short of calling for mandates.

In addition to other criticisms about the unions’ role in conservative approaches to holding in-person classes since the start of the pandemic, some have recently questioned why unions called for in-person classes five days a week for the 2021-22 school year, yet hadn’t endorsed vaccine mandates.

The national teachers’ unions and the Biden administration have touted survey data showing that about 90 percent of teachers are vaccinated, following efforts by both the AFT and the NEA, as well as the Biden White House, to increase vaccinations among educators as well as students.

However, an EdWeek Research Center Survey from this summer found that 11 percent of teachers said they don’t intend to get vaccinated against the virus.

It remains to be seen how much Weingarten’s personal backing for creating vaccine mandates for teachers affects local unions’ stances on the issue. Earlier this month, the teachers’ union for New York state came out against vaccine mandates for its members; New York State United Teachers is an affiliate of the AFT and NEA.

As coronavirus cases, hospitalizations, and deaths rise, political divisions about the new school year, and the best way for leaders and communities to handle masks and vaccines in particular, are growing. Such factors and tough decisions are creating a complicated and tense environments for school communities.

After the governors of Florida and Texas banned local districts from requiring students to wear masks, U.S. Secretary of Education Miguel Cardona criticized them in a White House press conference Thursday, saying that keeping students and school staff safe shouldn’t be politicized. Arkansas officials are also feuding over school mask mandates, and a judge in the state issued an injunction Friday that allows districts to institute mask mandates and puts a state prohibition on such mandates on hold, at least for now.

Weingarten also criticized governors opposing such mask mandates, saying they are hurting people.

The Biden administration recently announced new measures to try to boost vaccination rates for children ages 12 and up, amid concerns that vaccination rates for that age demographic is lagging.

“The combination of vaccines and masks I think will protect our youngest children,” Weingarten said on Meet the Press. “But we also have to work with parents.”