Mourners including President Donald Trump are preparing to honor the life of prominent conservative activist Charlie Kirk, 31, at a memorial service in Glendale, Arizona on Sunday.

Kirk, a close ally of the Trump administration and co-founder of Turning Point USA, was assassinated earlier this month while speaking at Utah Valley University in Orem, Utah. His death sparked an outpouring of grief and anger from the highest levels of government including Vice President JD Vance, who accompanied his coffin as Air Force Two transported his body home to Arizona, where Kirk lived with his wife, Erika, and two children.

Turning Point USA, which advocates for conservative politics on high school and college campuses, invited members of the public to don their "Sunday Best," specifically red, white or blue, for Kirk's memorial service at State Farm Stadium. Trump, Vance and other top administration officials, including Secretary of State Marco Rubio, are expected to be among those in attendance.

"Charlie’s life was short, but it was full. It was defined by truth, anchored in faith, and devoted to the country he loved," the organization's tribute to its co-founder reads. "His legacy will endure for generations."