The indictment was the subject of intense interest on K Street, where the Justice Department’s enforcement of the foreign lobbying requirements under the Foreign Agents Registration Act is widely seen as toothless. The charges against Mr. Manafort and Mr. Gates that are related to the act, coming as powerful members of Congress are demanding more enforcement of the law, were seen by some as a shot across the bow of Washington lobbyists.
Mr. Podesta, a major Democratic donor and lobbying powerhouse, announced his departure at a staff meeting on Monday, according to a partner at the firm who did not want to be identified discussing delicate internal affairs. He said that even before the announcement, some of the firm’s senior partners were trying to convince clients to remain with them as they worked to reintroduce the company with branding that would not include Mr. Podesta’s name.
The partner added that the effort had been fueled partly by Mr. Podesta’s aggressive efforts to defend himself against coverage by the conservative news media on the special counsel’s scrutiny of the Podesta Group.
Mr. Podesta’s lawyer on Monday sent a cease-and-desist letter to a Fox News host over his claims on air that Mr. Podesta and his brother, John Podesta, who served as chairman of Hillary Clinton’s 2016 presidential campaign, worked closely with Mr. Manafort on behalf of Russia. The host, Tucker Carlson, said that the Podesta brothers and Mr. Manafort were the “central figures” in Mr. Mueller’s investigation.
Mr. Podesta’s lawyer, Geoffrey R. Garinther, wrote to Mr. Carlson that his “false and defamatory statements have caused damage and injury to the reputation of Mr. Podesta and the Podesta Group.”
The indictment on Monday did not name the Podesta Group or Mercury, instead referring to them as “two Washington, D.C., firms” that were recruited by Mr. Manafort and Mr. Gates “to lobby in the United States on behalf of Yanukovych, the Party of Regions, and the government of Ukraine.”
Mr. Podesta and a spokesman for his firm did not respond to requests for comment.
Mercury said in a statement that it “takes its obligations to follow all laws, rules and regulations very seriously” and “has and will continue to fully cooperate with the Office of the Special Counsel in its investigation.”
The companies were paid more than $1.1 million each, according to lobbying filings, to try to rally support among American policymakers and opinion leaders for Mr. Yanukovych, and to quell concerns about his leadership and his government’s jailing of a political rival.
Neither firm initially registered with the Justice Department under the Foreign Agents Registration Act, which requires firms that lobby or conduct public relations for foreign individuals, companies, governments and political parties to reveal detailed information about their work.
The Podesta Group and Mercury said they relied on assurances provided by the nonprofit group that it was neither funded nor controlled by any foreign government or party.
But both firms were compelled this year to belatedly — and, in the case of Mercury, begrudgingly — register under the act, after their activities came under scrutiny from the Justice Department.
In its statement, Mercury said it followed the advice of legal counsel in its disclosure of its relationship with the European Center and noted that it registered the relationship under less detailed congressional lobbying disclosure rules. The Podesta Group also reported its relationship with the European Center under those disclosure rules.