The nation's chief executive is 50 years old today. At a celebration last night in Chicago, Jennifer Hudson sang 'Happy Birthday' to President Obama.

The Grammy-winning performer led the crowd of 2,400 in a singalong to wish the president a happy 50th. The birthday celebration was a fundraising event for Obama, with tickets ranging from $50 to $35,800, CBS reports. Musicians Herbie Hancock and OK Go also performed.

Before going on stage, Hudson tweeted, "Getting ready to sing for our president bday Chicago celebration n preparing for my baby 2nd bday n Chicago. Then next bday is mine !" Her son David turns 2 on Aug. 10, and J-Hud turns 30 on September 12.

Hudson's latest album, 'I Remember Me,' was released in March and earned Gold certification. Hudson has performed for Obama before, at other fundraising events and at the 2010 Celebration of Music from the Civil Rights Movement.

Watch Jennifer Hudson Sing 'Happy Birthday' to President Obama