Ahead of the Illinois Democratic primary on Tuesday, Democratic candidate Sen. Bernie Sanders has made it clear who he likes in Chicago, and who he doesn’t.

This past weekend, the Vermont senator blasted Chicago Mayor Rahm Emanuel for, among other things, closing public schools in the city, according to the New York Times. Sanders also blasted Emanuel for hurting the Windy City’s teachers by “luring the school system” into an exotic debt-finance scheme.

“Hillary Clinton proudly lists Mayor Rahm Emanuel as one of her leading mayoral endorsers,” Sanders told the paper. “Well let me be as clear as I can be: based on his disastrous record as mayor of the city of Chicago, I do not want Mayor Emanuel’s endorsement if I win the Democratic nomination.”

The debt-finance approach mentioned by Sanders refers to the decision by Chicago schools, during former U.S. Secretary of Education Arne Duncan’s tenure as the district’s CEO, to raise $1 billion by floating securities based on interest-rate swaps, instead of more traditional bonds. (What’s an interest-rate swap? The Khan Academy can help answer that.)

The Chicago Tribune reported in 2014 that the decision had ultimately backfired on the district.

As for the school closures—Emanuel has overseen the closure of about 50 schools in the Chicago system, but those closures helped fuel an electoral campaign against the mayor that forced him into a run-off election last year. Emanuel ultimately beat his challenger, Jesus “Chuy” Garcia, in that election.

Sanders feels differently about the Chicago Teachers Union, however.

He’s backing an April 1 event in which the union wants, among other efforts, to shut down classrooms in the city. The union, which isn’t calling the event a strike, says the event is necessary in order to highlight Emanuel’s mismanagement of the schools and the city as a whole, and his relationships with wealthy business leaders.

Sanders tweeted out his support of the April 1 event last week:

I stand with Chicago teachers. We shouldn’t close schools and lay off teachers to reward Wall Street. https://t.co/4EH0myWyzw

— Bernie Sanders (@BernieSanders) March 10, 2016

During a Democratic town hall event broadcast on CNN on Sunday, Sanders said he supported neighborhood public schools because they brought students from various backgrounds together. (Not everyone agrees with that characterization of how well such schools integrate communities.)

He was less sanguine about charter schools—during the same event, Sanders said he supported “public charter schools” but not “privately controlled” charters. Charters are by definition public, although some states allow private, for-profit organizations to manage charters or provide services to them.

Sen. Bernie Sanders, I-Vt., smiles as he is asked about running for president during a news conference on Capitol Hill in Washington on April 29.--Carolyn Kaster/AP