According to Warwick, tonight's announcement will reveal a rule change that is intended to solve a problem that has vexed the Idol's producers since the show's inception.
"It's because of a problem, actually, that's been around since Season 1," Warwick told Idol host Ryan Seacrest during a Wednesday morning appearance on Seacrest's KIIS-FM radio show. "And we've talked about doing something about it -- in fact we tried it in another country to see if it would work first, we tried it in France -- and it does work so we're going to put that into work tonight."
Warwick's comments would appear to refer to Nouvelle Star, the French Idol edition that premiered in France in 2003 and is also produced by American Idol's FremantleMedia production company.
Last year, Nouvelle Star introduced a new twist in which the judges were given a one-time veto power right which allowed them save a contestant that would have been eliminated based on home viewer voting at any point during the season. The French judges ended up using it during the season's very first finals round, resulting in no one going home that week.
American Idol's judges presumably wouldn't be as trigger-happy, opting instead to save the veto right for use during one of the unexpected eliminations (Tamyra Gray, Jennifer Hudson, Chris Daughtry, Michael Johns, etc.) that seems to occur during each Idol season's later rounds.
"Tomorrow night, [we'll announce] a surprise change to the rules that could alter the face of the competition," Seacrest said before asking Cowell if he felt viewers would like the change.
"Well it involves us [judges], so I'm not sure," Cowell responded.
"It kind of changes the entire theme and concept of the show," Seacrest told Cowell.
"You'll see tomorrow," said Cowell.
During his interview with Seacrest, Warwick also reiterated last night's announcement that two Top 13 finalists will be eliminated on tonight's results show.
"Obviously two are going to go today, which is kind of a change-up, but we can cope with that, that's fine," Warwick said. "It's the new rule that is going to come up tonight that is going to be the big talking point."
Fox reality chief Mike Darnell had first teased the "big surprise" back in January.
"There's a big surprise coming when we get to the Top 12, but I can't reveal it right now," he told TV Week at the time. "It is something that will be talked about and is something I think that has some element of controversy surrounding it."
While Darnell had declined to reveal specifics about the eighth-season surprise, he had hinted that it would not impact the show's "core."
"It's not going to change what you think of American Idol and we don't want to do that," he told TV Week. "This show is, you know, a phenomenon. It's American, it's apple pie. We're not changing the core of the show."