AFT President Randi Weingarten said during the call that the AFT executive council, at this week’s meeting, voted to step up member engagement in the election, according to the union. The council encouraged “locals and state affiliates to support, be actively involved with, or endorse” the three candidates ahead of the selection of more than 60 percent of the delegates by the end of March.

“The resolution signals to members and leaders that support for any of those three candidates is welcome at this stage of the process before the union makes a national endorsement,” the union said.

A second teachers union, the larger National Education Association, has not yet made an endorsement or other type of announcement about its support.

Weingarten, in a statement, said that while several candidates share the union members’ values, Biden, Sanders (I-Vt.) and Warren (D-Mass.) in particular have “significant support” with members. She cited a “real connection” with the candidates because of their records of working with the union on public education, higher education, labor and civil rights.

“It was clear that the time to take this action was now, before all the delegates are chosen and before all of the primaries are over, so that AFT members and leaders can help shape the race and the narrative, ensure our voices are heard, and ensure one of these three candidates emerges as the nominee,” Weingarten said.

The AFT is comprised of not only elementary and secondary school teachers and paraprofessionals, but health care workers, higher education faculty and staff and public employees.

The union’s endorsement process has included a public education forum it co-hosted with seven candidates in Pittsburgh, 10 candidate town halls across the country, member surveys and polls and other activities.

Several AFT local and state federations have already made candidate endorsements.

Warren landed hometown support from the Massachusetts chapter of the American Federation of Teachers and the Boston Teachers Union. Scranton Federation of Teachers, an AFT affiliate, is backing Biden, who was born and raised in Scranton until he moved at age 10 to Delaware.

In November, Sanders scored the endorsement of the United Teachers Los Angeles, an affiliate of NEA and AFT, representing about 35,000 educators.