New York federal prosecutors are considering charges against former Obama White House counsel Greg Craig in a probe linked to Paul Manafort, according to a published report.

Prosecutors in the US Attorney’s Office for the Southern District of New York may also take action against well-connected law firm Skadden, Arps, Slate, Meagher & Flom LLP, where Craig was a partner during the activity in question, CNN reported.

The probe centers on whether Craig improperly performed lobbying work on behalf of a group associated with Ukraine without registering with the Justice Department as a foreign agent, the CNN report said.

The investigation is tied to special counsel Robert Mueller’s Manafort probe because Manafort “solicited a law firm” on behalf of then-president of Ukraine Viktor Yanukovych, the CNN report said.

An attorney for Craig said the former Obama counsel “was not required to register under the Foreign Agent Registration Act.”