The American Federation of Teachers is encouraging its affiliates to support former Vice President Joe Biden, Sen. Bernie Sanders of Vermont, and Sen. Elizabeth Warren of Massachusetts in the Democratic presidential primary.

The AFT’s decision, announced by the union Thursday evening, was the result of a vote by the teachers’ union’s board of directors. Specifically, the union encouraged state and local affiliates “to support, be actively involved with, or endorse” Biden, Sanders, and Warren.

In its statement, the union also indicated its decision to back the three candidates in this way is not the last word in terms of an AFT endorsement. Rather, the organization said, “Support for any of those three candidates is welcome at this stage of the process before the union makes a national endorsement.”

“There is a real connection with these three candidates because of their record of working with us over the years on public education, higher education, healthcare, labor and civil rights,” AFT President Randi Weingarten said in a statement explaining the decision.

Weingarten noted that several AFT affiliates have already endorsed candidates. Examples of this include the United Teachers Los Angeles, which endorsed Sanders last November, and the AFT’s Massachusetts affiliate and the Boston Teachers Union, which both endorsed Warren last month. Sanders has also been endorsed by teachers’ unions for Clark County in Nevada (which includes Las Vegas), Oakland, and Washington, D.C.

In 2016, the AFT and the National Education Association both endorsed former Secretary of State Hillary Clinton in the Democratic primary. But both unions faced a backlash from some of their members who supported Sanders and thought the union did not give him due consideration. That vein of criticism continued after the 2016 presidential election.

Last March, the AFT shared its process for making an endorsement in the 2020 race. The union said this would involve “a candidate questionnaire, member surveys, focus groups with members, as well as town halls, social media forums, and more.” The NEA outlined its own endorsement process in May.

The two unions and other groups co-hosted a televised forum with several Democratic presidential contenders in December.

Last year, the Center for Responsive Politics reported that of the $3.6 million that teachers had donated to presidential candidates through the end of September 2019, a third of it went to Sanders, and that Sanders received more money from those in the education field overall than any other candidate. Warren came in second, while Biden came in fifth.

Photo: American Federation of Teachers President Randi Weingarten (Cliff Owen for the Associated Press)