Ryan Seacrest, Ellen DeGeneres, Others Congratulate Simon Cowell

Jordin Sparks, Kara DioGuardi and more comment on 'American Idol' departure.

Usually, when you quit a job, you pack your bobbleheads into a box and try to slip out the door as quietly as possible. But when your name is Simon Cowell and you're quitting America's most popular TV show, slipping out is not an option.

Reaction to Cowell's announcement on Monday that he was leaving "American Idol" after this season has created a Twitterstorm of comments from his co-stars and former "Idol" contestants. Just moments after the announcement on the eve of season nine's debut, host Ryan Seacrest tweeted, "This is Simon's last season on 'Idol.' He's working on U.S. version of 'X Factor'! He is one of the most brilliant people in our biz! Congrats."

A short while later, Seacrest, who is interviewing Cowell on his radio show on Tuesday (January 12), promised to ask the acerbic Brit if he's going to bring former "Idol" judge Paula Abdul along with him to "The X Factor" when it launches in the fall of 2011. "Simon just called from the car," he wrote a short time later. "We are going to have fun this season. ... He said Randy's reaction was ...'Yo, yo, YO' and a heartfelt 'dawg.' "

While Abdul did not directly respond to the news, she did drop a cryptic hint on her Twitter feed: "Hey Guys! I'm not ignoring all of your tweets regarding me, 'X Factor' and Simon leaving 'AI.' I look forward to being able to answer all your questions very soon!"

Ellen DeGeneres, meanwhile, spoke about the news while taping Tuesday's episode of her talk show. "He announced he's leaving on my first day," she said in a video posted on her site. "I'm trying not to take it personally. He wanted a change and I wish him all the luck in the world hosting 'The Tonight Show.' "

Judge Kara DioGuardi told Los Angeles' 104.3 MyFM that she had no idea about the announcement until just before it happened. "He's so important to the show," she said. "I think I was a fan before I was on the show, and he will be really missed."

Season-six winner Jordin Sparks expressed her disappointment about the news, writing, "It's sad because a lot of people watch because of him, but it was bound to happen eventually. And I may even miss him a little. :)"

In a testament to Cowell's influence, none of the former contestants who've commented so far have had any unkind words for the judge (who often has plenty of them).

"Of course, it is sad to see Simon Cowell leave 'American Idol,' " season-seven third-place finisher Syesha Mercado told "Idol" fan site AInow.org. "He is one of the reasons why 'American Idol' has become so successful. While on the show, I always valued Simon's opinion. It was honest and as a contestant that is something you have to appreciate. There will always be a special spot in my heart for Simon. During my time on 'Idol,' he was always kind to me."

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