Sen. Cory Booker, D-New Jersey, wasn’t saying whether he would support the confirmation of Betsy DeVos, despite having worked with her on education issues in the past.

At an event to discuss criminal justice reform at Google’s Washington office on Thursday, Booker voiced his concerns about President-elect Donald Trump’s selection of Sen. Jeff Sessions as attorney general.

But he took an indirect route when asked about DeVos, who Trump announced as his choice for secretary of Education, comparing his work with DeVos to his relationship with New Jersey Gov. Chris Christie, an early backer of Trump.

“I found partners on both sides of the aisle, whether it was the Manhattan Institute or Chris Christie,” Booker. “If Chris Christie was up for some position, trust me, just because I partnered with him in the past doesn’t mean that I would be voting for his confirmation.”

Pressed whether he would support DeVos, Booker replied, “I’m not saying anything. Jeff Sessions, as I said here, deserves a fair hearing, but I have serious concerns about the kind of people Donald Trump has been choosing and when the time comes, I’d be happy to sit down for an interview when that’s on the floor.”

While he was mayor of Newark, Booker sat on the board of the Alliance for School Choice while DeVos was chairwoman. He also addressed the 2012 national policy summit for the American Federation for Children, on which DeVos served as chairwoman of the board of directors.