CHICAGO (AP) - Jury selection was set to start Friday in the long-delayed trial of one of urban music's biggest stars.

Grammy-winning R&B singer R. Kelly faces child pornography charges, prompted by a videotape allegedly showing him having sex with a girl as young as 13.

The trial has been delayed for six years and another delay was possible after defense attorneys filed a motion Wednesday seeking to postpone the trial again. Judge Vincent Gaughan could rule on that request Friday.

The reasons for the motion were being kept secret, but it came as publicity surrounding the case heats up and some media speculated about who might testify.

Several Kelly detractors showed up on the courthouse steps Friday, saying they wanted to express support for victims of child pornography. Meanwhile, scores of photographers and cameramen were outside amid tighter security.

Prosecutors will have to surmount several hurdles if they hope to prevail.

Chief among them is that the alleged victim, now 23, says it wasn't her. And Kelly's lawyers - including prominent Chicago attorney Ed Genson - haven't admitted it's Kelly in the video.

The 41-year-old Kelly, who has pleaded not guilty, faces up to 15 years in prison if convicted.

The centerpiece of the trial is the video footage, which Gaughan ruled may be shown in open court.

Prosecutors claim the videotape was made sometime between Jan. 1, 1998, and Nov. 1 2000, and that the girl was born in September 1984. Kelly was indicted on pornography charges June 5, 2002, after the tape surfaced.

It is unclear whether prosecutors have asked - or would be allowed - to tell jurors about accusations that Kelly allegedly had sexual relations with other minors, because some of the trial proceedings have been kept secret by the judge.

Media outlets, including The Associated Press, have filed a motion seeking to get court records and hearing transcripts unsealed. Gaughan said Thursday he would rule on that motion May 16.

Once the trial gets under way, it is expected to last at least several weeks.

Although he won a Grammy in 1997 for the gospel-like song "I Believe I Can Fly," Kelly's biggest hits are sexually charged songs like "Bump N' Grind," "Ignition" and his current single, "Hair Braider." He is due to release a new album in July.