Capitol Hill is watching Sen. Cory Booker (D-NJ) as he twists and turns to handle the nomination of Elizabeth “Betsy” DeVos to lead President-elect Donald J. Trump’s Department of Education.

Cory Booker once served with DeVos on the board of the Alliance for School Choice, and the two had been considered political allies in the education reform debate.

However, Booker also has political ambitions, and at the highest levels of the Democratic Party, no one challenges the dominance of the public school teachers and their unions. Ideas like “school choice” or support for alternative and charter schools are heresies to the teachers and their unions, and it is becoming awkward for Booker to stay true to his previous positions and his relationship with DeVos.

In a Dec. 14 interview with The 74, a childhood education blog, the senator said he was not comfortable with DeVos:

“It is no secret that I strongly believe we have a lot of work to do to ensure that every child in America has access to a high-quality public education. I greet Ms. DeVos’s nomination with a healthy skepticism, and I have serious early concerns,” Booker said. “Like all of Trump’s nominees, I will approach her nomination with deep scrutiny, especially because I am alarmed by President-elect Trump’s overall education agenda and fear that he has little respect for — or interest in — the critical work that the Department of Education performs for our children.

But Booker was not always so concerned. The senator and former Mayor of Newark, New Jersey, has carved out for himself a niche where he is less doctrinaire on educational issues and often speaking at educational reform events focused on changing an education establishment and practices dominated by unionized public school teachers — a group that is among the top financial supporters of Booker’s own Democratic Party.

When Booker spoke at the May 16 meeting of the American Federation for Children, an advocacy group led by DeVos, Booker was anything but “concerned.”

So happy to be here, this is the first time I’ve gotten to come back to this incredible organization since I’ve been elected to United States Senate; and my experience over the years coming to this to this conference, coming to meetings, meetings of incredible folks who really believed in me when I was at the start of my career there are some people in this room who really were the difference makers as I was climbing the ladder in Newark, New Jersey, with a vision for transforming that city.

After the President-elect named DeVos, teachers unions and other Democrats were quick to call DeVos “right-wing.” When Booker spoke at AFC’s 2012 policy summit, he said the “right-wing” label was all wrong: “I’m like, ‘right-wing?’ I said, ‘First of all, I got lots of Democrats that are involved in this organization.'”

Booker told the summit he was tired of all the partisanship surrounding the education movement: “This country’s become much more about what party you’re a part of than about the progress, and the possibilities, the dreams, the plans. I’m tired of partisanship. Partisanship doesn’t serve my city; we’ve had Democrats representing our city for as long as I can remember,” he said:

I cannot ever stand up and stand against a parent having options because I benefited from my parents having options. And when people tell me they’re against school choice, whether it’s the Opportunity Scholarship Act or charter schools, I look at them and say, “As soon as you’re telling me you’re willing to send your kid to a failing school in my city or in Camden or Trenton, then I’ll be with you.”

DeVos testifies Jan. 11 in front of the Senate Health, Education, Labor, and Pensions Committee as part of her confirmation process.

Booker is not a member of the committee.

Watch Sen. Cory A. Booker (D-NJ) speak at the 2016 American Federation for Children Policy Summit: