The Amgen Tour of California has strengthened its anti-doping program to start prerace testing earlier and have the U.S. Anti-Doping Agency, not cycling's governing body, oversee in-competition testing starting this season.

The Tour of California race, which takes place from May 15-22, dropped a provision that excluded riders who were the subject of a pending doping investigation. Tour of California officials were peppered with questions Wednesday about how the rule change might affect the participation of Lance Armstrong, who has yet to say whether he will compete.

A federal grand jury in Los Angeles has been hearing evidence for months on cheating in professional cycling. The investigation turned toward Armstrong - and several of his associates have testified - since former teammate Floyd Landis accused him of systematic doping. Armstrong has always denied using performance-enhancing drugs.

USADA CEO Travis Tygart said his organization wanted the rule rescinded because it violated athletes' due process.

AEG Sports president Andrew Messick said teams would have to submit a provisional list of 12 cyclists in the next few days, and all those riders would be subject to testing for the three months leading up to the 2011 Tour of California race. But he acknowledged it would be possible for a rider who was not on the list to compete.

He said entrants were tested as part of the 2011 Tour of California starting only about 10 days before the event in the past. USADA believes doping is most likely to occur in the lead-up to a competition.

USADA had also pushed for testing by an independent agency, not the International Cycling Union (UCI) and its potential conflict of interest.