NEW YORK — A lawyer for Lev Parnas, whose activities in Ukraine have become a key focus on the eve of President Trump's impeachment trial, has asked Attorney General William P. Barr to recuse himself from Parnas's criminal case, suggesting the top Justice Department official is too enmeshed in the overarching political scandal.

The request — made Monday in the form of a letter to Barr — was filed by attorney Joseph A. Bondy in the Southern District of New York on the heels of a media blitz during which Parnas detailed his attempts to pressure Ukrainian leaders into announcing an investigation into former vice president Joe Biden.

Parnas has said he acted at the direction of the president’s personal lawyer Rudolph W. Giuliani and that Trump and Vice President Pence were aware of his activities. All three have disputed Parnas’s claims.

Parnas recently provided Congress with text messages and other digital records that were seized and later released by federal authorities as part of his criminal case.

Federal prosecutors here have accused Parnas and another Giuliani associate, Igor Fruman, of violating campaign finance laws by funneling foreign money to U.S. politicians while trying to influence U.S.-Ukraine relations. Both have pleaded not guilty, and Parnas has waged an aggressive public campaign to appear helpful to Democrats seeking Trump’s removal from office.

In the letter to Barr, Bondy wrote that “due to the conflict of interest of your being involved in these matters as Attorney General, and in an effort to preserve the public trust in the rule of law, we request that you recuse yourself and allow the appointment of a special prosecutor from outside the Department of Justice to handle this case.”

A Justice Department spokeswoman declined to comment.

Bondy’s letter to Barr cites references to Barr in Trump’s July phone call with Ukrainian President Volodymyr Zelensky, a conversation at the heart of Democrats’ case for impeachment.

A rough transcript of the call shows Trump offering Zelensky the assistance of his attorney general to facilitate an investigation of Biden.

The letter also notes that Democrats on the Senate Judiciary Committee, as well as the New York City Bar Association, have called for Barr to recuse himself from matters tied to the Ukraine scandal.

Justice Department officials have sought to distance the attorney general from the White House and Giuliani on matters connected to Ukraine, with Barr’s allies confiding to reporters last year that he was frustrated with Giuliani for using unconventional channels to pursue investigations of interest to the president.