Trainer John Quinn is poised to wait until the new year before bringing Character Building back into action after the grey suffered a training setback.
The nine-year-old landed the Kim Muir at Cheltenham in March and was on course to return in the Hennessy Cognac Gold Cup later this month.
However, Quinn has scratched the gelding after he missed some work.
"He's had a very slight setback - it's something over nothing reall," he said. "But he'll still miss a week's work so we'll have to give it a miss.
"I don't know what we'll do next as he wouldn't want a slog over three miles, five furlongs in heavy ground - like in the Welsh National.
"He seems a better horse in the spring anyway."
Denman remains the top weight as he looks to regain his crown in the race, ahead of 2008 hero Madison Du Berlais and the classy Irish horse Notre Pere.
There were 55 horses left in the Newbury feature on November 28 with the sidelined Air Force One and Trafford Lad amongst 29 taken out at the latest forfeit stage.

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