Barack ObamaBarack Hussein ObamaMomentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina Majority of voters say Trump should not nominate a Supreme Court justice: poll MORE is scheduled to address the nation's largest union, the National Education Association (NEA), at its convention this weekend.

The NEA, the union for public school teachers, has 3.2 million members. It will vote on a presidential endorsement Friday at its convention in Washington. Members are expected to endorse Obama.

The Illinois Democrat will speak via satellite feed Saturday at 10:15 a.m.