"Chairman Grassley and Ranking Member [Dianne] Feinstein have made clear that they intend to hear from all witnesses…. Of course the preference would be voluntary cooperation, however Chairman Grassley has been authorized to compel testimony, if necessary, from the witnesses," Foy said in an email released by The Hill on Friday.
Foy noted that the panel has been maintaining contact with both Trump Jr. and Manafort during this week. However, the president's son and his ex-campaign manager have not responded to the invitation to testify yet.
Earlier this month, US media reported that Trump, Jr. met in June 2016 with Russian lawyer Natalia Veselnitskaya, expecting that she would present a sensitive information about Hillary Clinton, but quickly understood she did not have any relevant information, and the parties moved to the problem of the adoption of Russian children by US nationals, which was the main theme of the conversation.
On Wednesday, media reported that Manafort, Trump, Jr. and head of Hermitage Capital Management William Browder were scheduled to testify before the Committee on July 26 as witnesses in the panel’s Russia probe.
Russian officials have repeatedly denied the allegations of meddling in US elections, calling them absurd and created to deflect public opinion from pressing domestic issues.