Former president Barack Obama met New York mayor Zohran Mamdani for the first time on Saturday at a child care centre in New York.
The pair read 'Alone and Together' to preschoolers and led a singalong, including 'Wheels on the Bus'. Children replied with 'Soda Pop'.
The visit came just over a week after Mamdani marked 100 days in office. They did not take questions from reporters.
Obama, a leading Democratic voice, has offered to act as a sounding board for Mamdani, 34, whose agenda focuses on affordability and support for working families.
The mayor has also met Donald Trump twice since his election, though tensions have grown. Trump recently criticised Mamdani's policies and raised the prospect of cutting federal funding.