A politician with a long track record of supporting vouchers and other forms of school choice will seek the White House in 2020—on the Democratic ticket.

U.S. Sen. Cory Booker, D-N.J., announced Friday that he will seek the presidency. When it comes to education policy, Booker has an interesting and perhaps unique track record among the Democrats who will fight to take on President Donald Trump. Although much of that record was established before he was elected to the Senate in 2013, how he talks about that record, and how teachers' unions react to his candidacy, will be worth watching.

Before coming to Congress, Booker was the mayor of Newark, N.J., from 2006 to 2013. During that time, he made his support for various forms of choice one of the key issues of his administration. In 2012, for example, we highlighted Booker as an example of how vouchers had gained a political foothold among Democrats at the state and local level. That year, he gave a speech to the American Federation for Children, a group formerly led by Secretary of Education Betsy DeVos (more on her in a moment) that supports vouchers, in which he said that many children "by law are locked into schools that fail their genius." And he co-founded a group, Excellent Education for Everyone, that backed charters and vouchers in New Jersey but fell short of its goals.

During his early political career, Booker also garnered support from Wall Street donors who took an interest in education policy. That group of donors eventually helped start Democrats for Education Reform, a group that supports charters and other forms of public school choice—Booker has served on its advisory board. However, some in the education community are suspicious of Booker's Wall Street ties.

Booker also grabbed headlines for partnering with Facebook founder Mark Zuckerberg, who donated $100 million to Newark schools during Booker's tenure as mayor to help support a new teachers' contract in the city, closed under-enrolled schools, and open new charters. But results from Zuckerberg's gift have been mixed, sparking sharp disagreements among those who participated in it. Zuckerberg has expressed regret about how his philanthropy in Newark schools did not include community members and teachers like it should have.

Because of his work to support a new Newark teachers' contract that included merit pay, Booker has often clashed with teachers' unions, who did not endorse him in the 2013 special election in which Booker won his Senate seat. And in 2010, the Newark teachers' union openly opposed his mayoral re-election bid.

During his time in the Senate, Booker hasn't focused much on education policy, although he has tried to simplify the financial aid process for college students, and worked to provide relief for teachers who have student loan debt. But it's how he's handled DeVos that's probably attracted the most attention.

As he did in 2012, Booker spoke at DeVos' American Federation for Children in 2016, and told the audience that Newark had become a "cauldron of educational creativity" that was "liberating the choice of our parents."

Yet Booker voted against DeVos' nomination in 2017, saying that the answers she gave in her confirmation hearing about special education concerned him. And in explaining his opposition to her nomination, he also cited the need for the head of the U.S. Department of Education to protect students' civil rights.

In general, he hasn't talked as much about his support for choice in the last few years, especially his previous backing for vouchers. It will be worth watching to see if Booker is pressed by allies and the media about his record on vouchers and his previous relationship with DeVos.

Photo: Sen. Corey Booker, D-N.J., addresses the Human Rights Campaign National Dinner reception in Washington in 2018. --Cliff Owen/AP-File