A waterlogged track prevented racing on Tuesday or Wednesday
The rest of York's Ebor Festival has been cancelled after an inspection of the course.
Full story to follow after two days were lost to bad weather.
Heavy rain meant no racing was possible on the first two days of the meeting, which includes the Juddmonte International Stakes.
Festival organisers may extend racing to Saturday or even use an alternative venue if conditions do not improve.
Around 100,000 racegoers were expected to attend the four-day meeting.
King George winner Duke of Marmalade and Derby hero New Approach had been set to go head-to-head in the Juddmonte, and other high-profile races on the card include St Leger trial the Ladbrokes Great Voltigeur Stakes and the Tattersalls Millions Acomb Stakes.
"It is extremely frustrating for everyone and we are looking at options for Thursday and Friday," said clerk of the course William Derby.
"We are still hoping to race then and if we get a dry 24 hours then we are still hopeful of racing Thursday and Friday.
"We are also considering racing on Saturday and going through the implications and logistics of taking that unprecedented move.
"We are also looking at whether we can stage extra feature races on Thursday and Friday, including the totesport Ebor. We are making every effort to do that as it is our feature race.
"Ruth Quinn, the British Horseracing Association director of racing, is in York and she is contacting other people including the Levy Board, other racecourses concerned and the broadcasters and those conversations are on-going."
The clash between Duke of Marmalade and New Approach was due to be the highlight of the festival.
Duke Of Marmalade has chalked up four Group One wins this season, while New Approach has not run since his triumph at Epsom in June.
Former champion trainer Henry Cecil was hoping for a third success in the race, with both Multidimensional and Phoenix Tower named in the 11-strong field for the 10 furlong race .
John Gosden's Pipedreamer was also declared but but Gosden said he would only run if the ground was suitable.
Sir Michael Stoute had Linngari and Rob Roy entered while Mick Channon also had two runners in Championship Point and Halicarnassus.
David Elsworth's Stubbs Art, third in both the English and Irish Guineas, and Duke Of Marmalade's stable companion Red Rock Canyon complete the line-up.