President-elect Trump's attorneys have accused a member of the New York jury that convicted him of wrongdoing, seeking to overturn the historic guilty verdict.

In a letter to Judge Juan Merchan unsealed Tuesday, Trump attorneys Todd Blanche and Emil Bove claimed the legal team has "evidence of grave juror misconduct during the trial."

"The jury in this case was not anywhere near fair and impartial," they alleged.

But prosecutors with the Manhattan district attorney's office called the allegations "untested" and "unsworn," casting the revelation as an effort to undermine public confidence in the case.

Details of the allegations were heavily redacted and concealed from public view. Merchan said in a separate letter that he ordered the redactions to ensure the safety of jurors, who have remained anonymous, and preserve the case's integrity.

Prosecutors said the claim by Trump’s attorneys stemmed from email exchanges between the defense and an unnamed whistleblower. 

The full exchanges were not attached to the letter, they said, but excerpts apparently showed the whistleblower saying that the defense’s version of events “contains inaccuracies and does not contain additional information that I never shared.” The person declined to endorse the defense’s version and ceased communication with Trump’s counsel, prosecutors said. 

“As such, it cannot be determined which of the allegations counsel believe they heard are accurate,” wrote assistant district attorney Joshua Steinglass. “This is precisely why the law requires sworn allegations of fact to seek dismissal on a claim of juror misconduct.”

Trump spokesperson Steven Cheung said in a statement to the Associated Press that "partisan political motivations infected nearly every aspect of this Witch Hunt, including the jury room," implying that a juror may have expressed political views. The Hill requested comment.

Prosecutors questioned the defense’s motives for raising their claims in a letter to the judge but not filing a formal motion to dismiss the case and opposing a hearing on the matter. 

Trump's attorneys argued that such a hearing would likely require "extensive, time-consuming and invasive fact finding." It would be "the type of 'extended proceeding' that the Presidential immunity doctrine forbids, which would impose additional disruptive and constitutionally unacceptable resource burdens on President Trump during the transition process and following inauguration as he carries out his vital duties as President," they wrote.

In a Dec. 16 letter to both parties, Merchan said he could not allow the public filing of "unsworn and admittedly contested statements" unless a proper claim is filed.

“Allegations of juror misconduct should be thoroughly investigated,” Merchan wrote. “However, this Court is prohibited from deciding such claims on the basis of mere hearsay and conjecture.”

The allegations of juror misconduct come as Merchan weighs a separate defense request to toss the case because Trump is now president-elect. The judge recently ruled that the case withstands the Supreme Court's new test regarding presidential immunity.

Trump was convicted on 34 counts of falsifying business records in connection with a hush money deal made with adult film actress Stormy Daniels to keep quiet about an alleged affair ahead of the 2016 presidential election. He has vowed to appeal.