The Insider.com

Heidi Klum revealed at a party for the upcoming 10th season of Project Runway that the bitterest dispute she ever had with the other judges was over her insistence that Mondo Guerra should have won season eight over Gretchen Jones.

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"The biggest disagreement ever, I have to say, was when Gretchen won, and we were fighting over Gretchen," Heidi told The Insider at a special launch party for the show's upcoming season 10. "And I really wanted Mondo to win and Michael (Kors) and Nina (Garcia) wanted Gretchen, and Jessica Simpson was there, and she also wanted Mondo -- but then they were so hammering on her that they won her over. So then the votes were 3-1."

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She explained that this instance was the most heated exchange she remembers in the history of the show, which debuts its new season this Thursday July 19 at 9 p.m. on Lifetime. "That was really the only time that we were literally fighting about it," she said. 

When asked about the judges' lasting chemistry, Heidi said there is really no magic formula. "We've kind of been like family together for 10 years, and I don't know, it just works." 

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Tim Gunn said he thinks the show has lasted so long because of the commitment of everyone involved. "Well, we're very loyal to the Project Runway brand," he said. "We are very proud of what we do and the outcomes of the show, and it's a thrill and a pleasure to be part of it. I mean for me it's a joy."

Watch the video for more from the glamorous season 10 launch party -- including the unveiling of "Project Your Runway," a 20-foot-long LCD-powered virtual runway featuring Heidi, Michael, Nina and Tim Gunn giving real-time video reactions to passersby as they strut their stuff down the digital catwalk on The High Line in New York.

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