Donald Trump cannot obtain a bond to secure the $454 million civil business fraud judgment against him as he pursues an appeal of the case, his attorneys said in a New York court filing Monday.

Attorneys for Trump and his co-defendants in the fraud case argued that it was “impossible” for them to secure a complete appeal bond, which would “effectively” require “cash reserves approaching $1 billion.”

“Defendants’ ongoing diligent efforts have proven that a bond in the judgment’s full amount is ‘a practical impossibility,'” the lawyers wrote, quoting an affidavit in the filing with the Appellate Division of Manhattan Supreme Court.

They said they have approached roughly 30 surety companies through four separate brokers, and that they have spent “countless hours negotiating with one of the largest insurance companies in the world.”

The lawyers said that if the appellate division considers denying the requested stay of the judgment, it should schedule oral arguments on the issue. And if the division declines to grant the stay, the lawyers asked that it allow them to file an appeal with the Court of Appeals, the highest state court in New York.

Manhattan Supreme Court Judge Arthur Engoron in February ordered Trump and his co-defendants to pay a total $464 million in damages and interest for violating a New York anti-fraud statute. Of that total, Trump was ordered to pay $454 million. Trump’s post-judgment interest continues to accrue at a rate of nearly $112,000 a day.

The case brought by New York Attorney General Letitia James accused Trump, his two adult sons, his company and its top executives of falsely inflating Trump’s asset values for years to boost his net worth and get financial perks.

The defendants had previously offered to post a $100 million bond, less than one-fourth the total judgment, in order to pause James from collecting the penalties during the appeal process.

Appeals court Judge Anil Singh rejected that proposal, but allowed the defendants to continue doing business in New York and lifted Engoron’s three-year ban on Trump seeking loans in New York. Singh’s order is temporarily in effect before a full appeals court panel hears the motion for a stay.

Trump’s attorney Alina Habba did not immediately respond to CNBC’s request for comment on the filing.

Trump earlier this month obtained a $91.6 million bond from the Chubb insurance company to secure a civil defamation judgment against him in favor of the writer E. Jean Carroll while he appeals that judgment.

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