A federal judge has ordered special counsel Robert Mueller to identify by Friday all the individuals and organizations involved in former Trump campaign chairman Paul Manafort's alleged scheme to lobby on behalf of Ukraine without registering as a foreign agent under U.S. law.

Among the people Mueller will be required to identify to the defense are top European former politicians who took part in the influence campaign in favor of the Viktor Yanukovych Government, as well as others whose testimony Manafort has been accused of trying to influence in recent months, according to Politico.

The ruling from U.S. District Court Judge Amy Berman Jackson Tuesday represents a rare courtroom win for Manafort's defense, which is battling Mueller's prosecutors in two different federal courts and faces two looming jury trials.

Prosecutors resisted the defense motion, but the judge's decision is not likely to be significant since many of the names are well known to the defense and have been reported in the media.

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For instance, former Italian Prime Minister Romano Prodi and former Austrian Chancellor Alfred Gusenbauer have acknowledged some involvement in paid lobbying work for Ukraine. However, they have said they were not paid by Manafort.

The witness-tampering claims prosecutors leveled at Manafort last week also pointed to the involvement in the lobbying campaign of individuals connected to a European public relations and TV production firm, FBC Media.

However, that list—once turned over—will effectively cabin the government's case on the foreign-lobbying issue since prosecutors will likely be unable to present evidence about businesses or people not on it.

The judge said that turning over the identities will aid the defense in preparing for the trial set for Sept. 17.

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Manafort faces charges of money laundering, failing to register as a foreign agent in connection with his Ukraine-related work, and obstruction of justice. The veteran lobbyist and political consultant is also confronting another indictment including charges of tax evasion, bank fraud and failing to report foreign bank accounts.

Manafort has pleaded not guilty to all the charges.