Still, some education leaders are hesitant to fully back the proposed legislation. Randi Weingarten, president of the American Federation of Teachers, joined several charter school leaders from across the country in writing a letter to Congress, urging lawmakers to adopt proposed amendments to the House bill that would enhance accountability and transparency.

"We know that when public charters are held to the same standards of accountability, equitable access and transparency as traditional public schools, all our students receive a better education," the letter says. "But when public charters are not held to these standards, student learning suffers and taxpayer money is wasted."

[MORE: New York and Illinois Head in Opposite Directions on Charter Schools]

The group pointed to a report released Monday that claimed charter school operators in 15 states were responsible for "losing, misusing or wasting over $100 million in taxpayer money."

"All institutions that receive public education dollars should be held to the same high standards, and we urge you to support improvements to this legislation that would ensure better financial oversight of charters, transparency with charter finances, and equitable access for and treatment of all students," the teachers continue in their letter.

One amendment to increase the accountability and transparency of charter schools – from Rep. Kathy Castor, D-Fla. – failed to pass. It would have required Education Secretary Arne Duncan to develop and enforce conflict-of-interest guidelines for any charter school receiving funds under the bill.

"The conflict-of-interest problems afflicting charter schools across the country endanger the outstanding work being done by many charter schools," Castor said Friday. "If charter schools are going to effectively carry out their mission for students using public funds, it is clear we need more accountability and better procedures in place to protect taxpayer investments." But Kline strongly opposed the amendment, saying it would be a federal overreach and that the bill sufficiently addresses concerns about conflicts of interest. [READ: AFT, Advocacy Group Want More Accountability for Charter Schools] "Simply put, this amendment is unnecessary," Kline said. "W "Simply put, this amendment is unnecessary," Kline said. "W

e do not need the secretary of education getting more involved in these schools by layering on more burdensome requirements. These are issues best addressed at the state and local level, and the underlying bill already provides support for these efforts."