The Senate Judiciary Committee has invited Donald Trump Jr. and former Trump campaign chairman Paul Manafort to testify before the panel next Wednesday.
Also invited to testify in the open session are Glenn Simpson, the head of the firm behind the dossier of anti-Trump research compiled by former British spy Christopher Steele, and Bill Browder, a London-based hedge fund manager.
The stated purpose of the hearing is to explore failures in the Foreign Agents Registration Act, though the event will likely include discussions about the June 2016 Trump Tower meeting and the Steele dossier.
Browder and Simpson had been scheduled to appear at a hearing that was initially slated for this Wednesday, but it was abruptly cancelled on Tuesday after the committee decided to add additional witnesses and obtain additional documents.
Special Counsel Robert Mueller reportedly gave the green light to the Judiciary Committee on Tuesday to interview Trump Jr. and Manafort in a public setting.
Trump Jr. and Manafort are of interest to the committee because of their June 9, 2016, meeting at Trump Tower with a Russian attorney who Trump Jr. was informed would be providing opposition research about Hillary Clinton.
Browder and Simpson became embroiled in the fallout over that meeting because the Russian lawyer, Natalia Veselnitskaya, was lobbying in the U.S. at the time against the Magnitsky Act, a sanctions law that blacklists Russians accused of human rights abuses.
Simpson, the co-founder of Fusion GPS, worked in coordination with Veselnitskaya on that lobbying campaign, which was financed by a Russian businessman who hoped to avoid sanctions.
Simpson was hired to investigate Browder, whose lawyer, Sergei Magnitsky, is the namesake for the sanctions bill. Browder is the leading activist behind passage of the Magnitsky Act in the U.S. and other Western nations.
Last July, Browder filed a complaint with the Justice Department accusing Veselnitskaya, Simpson and others of failing to properly file as foreign agents under FARA.
The same month of the Trump Tower meeting, Simpson and Fusion GPS hired former British spy Christopher Steele to begin researching Trump’s activities in Russia. Steele would go on to produce a 35-page dossier full of salacious but uncorroborated allegations.
Iowa Sen. Chuck Grassley, the chairman of the Judiciary Committee, has questioned Fusion GPS over its involvement in the dossier, which the FBI has reportedly used as a source document for part of its investigation into potential collusion between the Trump campaign and Russian government.
Grassley has called the dossier a political document because Fusion GPS was working last year for a supporter of Hillary Clinton’s.
So far, Browder is the only one of the four invitees who have committed to appear at the Senate hearing.
Last week it was reported that Simpson planned to skip the hearing scheduled for this week. It is also not known whether Trump Jr. and Manafort will attend.
A spokesman for Manafort said that the invitation was being reviewed. Trump Jr.’s lawyer did not immediately respond to a request for comment.