A team of heavy-hitter Democrats will be at the American Federation of Teachers conference this weekend to address educators: Hillary Clinton, Sen. Elizabeth Warren, and Sen. Bernie Sanders.

The biennial convention, which begins tomorrow, will be held in Pittsburgh, Penn. It's happening in the wake of a Supreme Court blow that is expected to significantly dent the treasuries and membership counts of teachers' unions. Justices ruled in Janus v. American Federation of State, County, and Municipal Employees Council 31 to prohibit "agency" or "fair share" fees, which unions had been charging to nonmembers in 22 states. Now, teachers don't have to pay any sort of fee to be represented in collective bargaining, so many are expected to leave the union entirely.

Still, at the National Education Association's yearly convention, which took place last week, union leaders were defiant as they planned a way forward. There will likely be a similar tone at the AFT meeting, which will emphasize both member engagement and political action.

"We are in a race, and the November elections are the key. The other side believes this is their moment to consolidate their power over our economy and democracy, and they are willing to spend whatever is necessary to take us out," wrote AFT President Randi Weingarten and other leaders in a letter to delegates.

The letter pointed to a messaging campaign funded by conservative groups that aims to get teachers to drop their memberships. In an essay for Education Week, Weingarten wrote that few AFT members have opted out of the union so far, and that since January, more than half a million members have signed cards recommitting to the union.

"[To] truly change America takes more than mobilization—it takes organization, persistence, and a sustained political effort," the letter to delegates concluded. "The national union provides that kind of organization and muscle."

Sanders and Warren are both rumored to be presidential contenders in 2020. They have both criticized the Janus decision.

The Janus case could tilt the playing field further in favor of corporations & make it much harder for workers to stand up for themselves. -- Elizabeth Warren (@SenWarren) September 28, 2017

School shooting survivor Mei-Ling Ho-Shing, a student at Marjory Stoneman Douglas High School in Parkland, Fla., is also expected to address AFT attendees. Classmate David Hogg addressed the National Education Association's annual convention last week, urging teachers to be civically engaged and to make sure their students are registered to vote.

The three other presidents of the country's major labor unions will speak at the convention, too: NEA President Lily Eskelsen García, AFSCME President Lee Saunders, and Service Employees International Union President Mary Kay Henry. Weingarten spoke at NEA's convention last week. The unions have vowed to work jointly to organize and engage their members.

For coverage on the AFT's convention, follow along here on Teacher Beat or on Twitter @madeline_will.

Image of Hillary Clinton via Andrew Harnik/AP-File