Special Counsel Robert Mueller issued subpoenas seeking testimony from executives who worked on a campaign organized by Paul Manafort – including the Podesta Group — an NBC exclusive report published Friday revealed.

The Podesta Group, co-founded by John Podesta, who was chairman of Hillary Clinton’s 2016 presidential campaign, was one of six lobbying firms that worked on Manafort’s campaign to get Ukraine into the European Union between 2012 to 2014 – a fact buried in the ninth paragraph of NBC’s report.

An executive, whose firm received a subpoena, said Mueller’s team is particularly interested in taking a close look at the lobbying campaign that included the Podesta Group.

“We think they are trying to figure out, was this a legitimate project?” the executive told NBC News. “From our perspective it was — we did a lot of work. We took it seriously.”

The unnamed executive told NBC News that six firms participated in the campaign that Manafort coordinated, which was paid for by the European Center for a Modern Ukraine, a non-profit based in Brussels.

The report states that two groups, the Podesta Group and Mercury LLC, worked in Washington with Manafort’s partner Rick Gates, according to lobbying disclosure records.

“At the time, Ukraine was run by a pro-Russian political party that had paid Manafort $17 million for consulting in 2013 and 2014,” NBC News added.

The Podesta Group belatedly filed multiple new disclosures with the Department of Justice (DOJ) related to their work in the Ukraine during Manafort’s campaign, the Washington Examiner reported on Thursday.

The recent August 17 filings by the Podesta Group include registration statements for six Podesta Group employees and a list of political contributions made by “relevant employees” throughout 2013.

The Washington Examiner also noted that the Podesta Group also belatedly filed documents in April that showed dozens of previously unreported interactions:

Back in April, the powerful Washington lobbying firm run by Clinton ally Tony Podesta filed a document admitting its work for the pro-Russia European Centre for a Modern Ukraine may have principally benefited a foreign government. New disclosures revealed dozens of previously unreported interactions the firm made with influential government offices, including Hillary Clinton’s State Department and the office of former Vice President Joe Biden, while lobbying on behalf of the center. The Podesta Group belatedly filed several new disclosures with the Justice Department on Aug. 17 related to work the firm completed between 2012 and 2014 on behalf of a pro-Russia Ukrainian think tank.

The Podesta Group’s most recent belated filing with the DOJ on August 17 came just one day after Politico reported that a “Ukrainian member of parliament requested a criminal investigation into possible meddling by his country’s government into last year’s U.S. presidential elections.”

Interest in these claims gained steam after President Trump tweeted a line from the original report.

Ukrainian efforts to sabotage Trump campaign – “quietly working to boost Clinton.” So where is the investigation A.G. @seanhannity — Donald J. Trump (@realDonaldTrump) July 25, 2017

Politico’s report, published January 11, 2017, alleged that Democratic officials worked with Ukraine to boost Clinton and harm Trump:

Ukrainian government officials tried to help Hillary Clinton and undermine Trump by publicly questioning his fitness for office. They also disseminated documents implicating a top Trump aide in corruption and suggested they were investigating the matter, only to back away after the election. And they helped Clinton’s allies research damaging information on Trump and his advisers.

The media has largely ignored any claims suggesting that the Democrats and Hillary Clinton may have received help from a foreign government during the 2016 presidential election.

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