When Senator Bernie Sanders delivered a wide-ranging speech on education Saturday, he became the first major Democratic candidate to propose a detailed plan to racially integrate schools, calling for $1 billion in funding to support local integration efforts, such as magnet schools and busing.

It was the type of robust agenda that integration advocates say they have waited decades for.

But for some, those ideas were overshadowed by more divisive elements of the proposal: Mr. Sanders’s plan to freeze federal funding for all new charter schools, and the link his plan made between charter schools and segregation.

Many Democrats, most notably Barack Obama, support charters as a way to provide more options to families, especially those that are too poor to move to a higher-quality school district or pay for private school. The impact of charters on school segregation is hotly disputed in education circles, and by linking these elements, Mr. Sanders touched a nerve in a highly charged debate within the party.

Blaming charters for school segregation is “galling,” said Amy Wilkins, a vice president at the National Alliance for Public Charter Schools and a longtime advocate in Washington for racial equity in education. “What Brown v. Board of Education did was say that government can’t tell black parents which public schools they can and can’t send their kids to. What Senator Sanders is saying with his attempt to limit charter schools is telling black parents, who overwhelmingly support charters, that they can’t send their kids to charters anymore.”