*President Barack Obama will deliver an opening message before the premiere of “Speak Up,” a Cartoon Network documentary about bullied youth across America and those who have helped them.

The half-hour film, part of the network’s “Stop Bullying: Speak Up” initiative, will be aired on Sunday at 5:30 p.m. EDT/PDT, with an encore at 8 p.m.

The film features appearances from athletes Venus Williams, Chris Webber, Lisa Leslie, soccer player Hope Solo, BMX bike rider Matt Wilhelm and NASCAR drivers Trevor Bayne, Jeff Burton and Joey Logano.

The film will also be available on www.StopBullyingSpeakUp.com  and via other outlets including Facebook, iTunes and YouTube after the premiere.

Obama, who has said he endured school-yard harassment, hosted the first anti-bullying summit at the White House last year.

Meanwhile, First Lady Michelle Obama will appear on the “Late Show with David Letterman” on March 19. She’ll discuss her Joining Forces initiative, which supports military families, and her plans for the program’s one-year anniversary.

This will be Mrs. Obama’s first appearance on the program. Her recent appearances include “The Tonight Show with Jay Leno” and Jimmy Fallon’s “Late Night” program. Both shows are on NBC.