AFT released a polling memo that showed its Democratic members favor Biden (60 percent) over Sen. Bernie Sanders (30 percent) as the party’s nominee. Seventy-five percent of members — who include teachers, higher education faculty and health care professionals — view Biden positively, a gain of five points since October, while Sanders’ positive rating has slipped 6 percentage points (to 66 percent) over the same period, according to the survey by Hart Research Associates.

The endorsement comes at a time of uncertainty in the primary process, with several states postponing voting. Instead of traditional phone banks, meetings and canvassing, NEA has moved to digital get-out-the-vote efforts, including emails, social media and digital ads to encourage members to vote.

Weingarten called the pandemic “the greatest challenge we have battled in generations,” and she blasted President Donald Trump and his administration for failing to secure testing and personal protective equipment to safeguard health care providers, concealing the severity of the virus and downplaying the public health risks. She said the administration has “refused to deploy the full arsenal” of federal resources, leaving leadership to governors.

“Now more than ever, we need a standard-bearer who is actually looking out for us, and who has a proven track record of steering the country successfully through economic and social upheaval,” she said.

AFT backed Hillary Clinton in the 2016 primary. The early endorsement didn't go over well with some of the rank-and-file members who supported Sanders and with other labor leaders, who questioned its timing.

Their endorsement this year follows candidate events, town halls, polls, regional conferences and other efforts to maximize member participation leading up to the November election.

The polling memo shows support for Biden “has consolidated throughout the union, making him the first choice of every constituency, every region of the country, and both men and women. He not only enjoys a large 46-point edge among moderate/conservative Democrats, but he also leads among liberal Democrats (+17).” Most members believe he can beat Trump.

Last month, AFT announced it would encourage its local and state affiliates to back or endorse the presidential bids of Biden, Sanders (I-Vt.) or Sen. Elizabeth Warren (D-Mass.) and Weingarten announced her “personal support” for Warren before she dropped out of the race.

Weingarten described Biden’s presidential candidacy in a November interview with POLITICO as being from “a different era.” People love that about Biden, she said, but it also means he’s “not as attentive to the cues of this era.”

On Sunday, she lauded Biden’s character and his plans for investing in public education, making college “a reality for everyone” and fixing the “broken” Public Service Loan Forgiveness program. She also said Biden is with the union on making health care a human right, prioritizing clean energy and environmental justice and building a pathway to the middle class.

“His whole career has been devoted to building a pathway to the middle class for the millions of people facing an affordability crisis daily. It’s time to give him the chance to do that as president,” she said.

Juan Perez Jr. contributed to this report.