U.S. Sen. Elizabeth Warren says while many charter schools produce "extraordinary results" for students, she plans to vote no on Question 2.
Question 2 if approved would allow for up to 12 new or expanded charter schools each year outside of existing state caps.
The Democrat said in a statement she is concerned about what the November ballot initiative would mean for hundreds of thousands of other students in Massachusetts, particularly those in financially-strapped school districts.
Supporters of the measure released a new TV ad on Tuesday rejecting claims by opponents that charter schools siphon money away from conventional public schools. Backers contend charter school growth leads to more state funding for public school districts.
Warren called on state legislators to create an education policy "without pitting groups against each other."