Democratic New York gubernatorial candidate Cynthia Nixon on Friday publicly announced that her son is transgender in a post congratulating him on graduating from the University of Chicago.

“I’m so proud of my son Samuel Joseph Mozes (called Seph) who graduated college this month,” Nixon wrote. “I salute him and everyone else marking today’s #TransDayofAction.”

The post came on the same day as Trans Day of Action, an annual rally and march held in New York City. It is organized by the Audre Lorde Project, an organization for LGBTQ+ people of color.

Samuel, who was born in 1996, is Nixon’s child with former partner Danny Mozes.

Nixon is a longtime advocate for LGBTQ+ rights and a member of the LGBTQ+ community. She is married to activist Christine Marinoni.

Nixon has faced public scrutiny over her sexuality. Last month, Former Speaker of the New York City Council Christine Quinn called her an “unqualified lesbian.” She later clarified she was only referring to Nixon's experience.

Nixon is running against New York Gov. Andrew Cuomo (D) in the Democratic primary.