First created in 2004, the D.C. voucher program has been the proverbial political football in Congress for years.
Experts and advocates are divided on whether Duncan's move will have a good, bad, or neutral effect on prospects of overhauling the Elementary and Secondary Education Act.
The endorsement comes despite serious misgivings from some affiliates, who were hoping a slower endorsement process would give the union more time to extract more policy promises from Clinton.
A former New York state commissioner of education, he will take the reins at the U.S. Department of Education following Secretary Arne Duncan's departure in December.
U.S. Secretary of Education Arne Duncan, who has pushed through a dramatic reshaping of the nation's education system, first through Race to the Top and then through a series of waivers from the No Child Left Behind Act, will step down in December.
The education secretary says that much could be saved by redirecting some non-violent offenders away from prison, and the money used to boost salaries at high-poverty schools.
Civil rights groups are running radio ads aimed at lawmakers who may play a key role in rewriting the No Child Left Behind Act.
The two national teachers' unions and the group representing state schools chiefs are among those saying now's the time to complete an Elementary and Secondary Education Act rewrite.
Earlier this year, the Lone Star State essentially seemed to be daring U.S. Secretary of Education Arne Duncan to pull its flexibility.
The California Republican, elected in 2006, doesn't have nearly as long a resume on K-12 as did current Speaker John Boehner going into the job.