WASHINGTON — The Trump administration is proposing “the most ambitious expansion” of school choice in American history, Education Secretary Betsy DeVos announced Monday while giving few details on how the program would work.

“We must offer the widest number of quality options to every family and every child,” DeVos said in a speech in Indianapolis. “We stand on the verge of the most significant opportunity we have ever had to drag American education out of the Stone Age and into the future.”

DeVos gave few specifics other than to say that the state of Indiana could serve as a model. Indiana has one of America’s largest and fastest-growing school voucher programs to give low-income families scholarships to help pay private school tuition.

DeVos insisted that decisions on school choice must be left for states, not the federal government, to make. But she also warned states against boycotting reform.

“If a state doesn’t want to participate, that would be a terrible mistake on their part. They will be hurting the children and families who can least afford it,” DeVos said at an event hosted by the American Federation for Children, the school choice advocacy group she used to lead. “If politicians in a state block education choice, it means those politicians do not support equal opportunity for all kids.”

Earlier this month, President Donald Trump asked Congress to work with him on expanding charter and private school voucher programs nationwide, but he gave no specifics. School choice advocates are divided over whether to push charter schools and vouchers on the federal or state level.

Voucher and charter school programs are facing fierce criticism from teachers unions and many Democrats, who believe they drain resources from already underfunded public schools while failing to produce clear academic gains.

“Once again, Secretary DeVos is putting her extreme privatization agenda ahead of our students,” said Washington Sen. Patty Murray, the top Democrat on the Senate Health, Education, Labor and Pensions Committee. “DeVos claims she wants to provide more choices for students and families, but in reality, voucher programs siphon taxpayer funds from public schools to unaccountable private and religious schools that often leave children worse off.”

WATCH: What will Betsy DeVos’ focus on school choice mean for public education?