Public school teachers' unions are skeptical of the charter school reform bill moving through the House this week, hinting at danger for Democratic support of the measure.

Although Rep. George Miller (D-Calif.), one of the most liberal members of the House, co-authored the bill, H.R. 10, with House Education and the Workforce Chairman John Kline (R-Minn.), others are not sold.

The Education Committee advanced the measure, which would consolidate the existing two federal charter school grant programs into one, by 36-3 in April. All of the votes in opposition came from Democrats, including Congressional Black Caucus Chairwoman Marcia FudgeMarcia Louise FudgeHouse rejects effort to condemn lawmaker for demanding 'Dreamer' arrests Hispanic Dems seek vote to condemn GOP lawmaker for demanding arrests of 'Dreamers' Dem lawmaker: ‘We are seeing the dumbing down of the presidency’ MORE (Ohio) and Congressional Progressive Caucus Co-Chairman Raul Grijalva (Ariz.).

Republicans have touted the issue of school choice and access to charter schools as a way of curbing the federal government's role in education. Charter schools receive public funding, but operate independently and therefore are not subject to federal regulations.

The American Federation of Teachers (AFT) indicated concerns that the bill wouldn't subject charter schools to federal education requirements, such as reporting student discipline policies.

"The Miller-Kline bill includes improvements over current law, but it doesn’t go far enough in requiring the oversight and transparency that is owed to the students who attend charter schools and to the taxpayers who financially support them," AFT President Randi Weingarten said.

The National Education Association (NEA), the largest professional employee organization in the U.S., expressed reservations as well.

"While we are encouraged the bill includes improvements in some areas over current law, it ultimately falls well short of long-overdue parent, student, educator, community and taxpayer safeguards needed in the now 23-year old charter sector," Mary Kusler, the NEA's director of government relations, wrote in a letter to House offices last month.

However, the NEA did express support for provisions that would create weighted lotteries for charter school funding and establish state oversight of charter school authorizers.