Charter schools were supported by the Obama administration and, in general, have had the support of Democrats.

Senator Cory Booker of New Jersey, who is also running for president, has been a strong supporter of charter schools. Last year, Mr. Booker said in an interview that “my loyalty is to a free public school, high-quality public school education,” allowing that charter and magnet schools could be part of the mix.

Other Democratic candidates have unveiled education plans in recent weeks. A proposal by Senator Elizabeth Warren of Massachusetts focused on higher education, with the goals of canceling most student loan debt and eliminating tuition at public colleges. Julián Castro, the former housing secretary, announced similar goals, as well as proposals to increase teacher pay and create a national, federally funded prekindergarten program.

Mr. Sanders revealed his plan one day after the 65th anniversary of Brown v. Board of Education, the Supreme Court decision that legally desegregated United States public schools. Its name, A Thurgood Marshall Plan for Public Education, invokes the lawyer who argued the case for the N.A.A.C.P. before he became a Supreme Court justice.

“Many U.S. schools remain unacceptably segregated,” Mr. Sanders wrote in the plan.

Mr. Sanders’s plan also explains that black students are nearly four times as likely to be suspended as white students — a disparity he attributes to “implicit racial bias” that also puts black youth at greater risk of becoming entangled in the criminal justice system.