Donald Trump Jr. and former Trump campaign chairman Paul Manafort have been scheduled to testify before the Senate judiciary committee on July 26, the panel announced Wednesday.

President Donald Trump's son-in-law Jared Kushner is also expected to appear before the Senate intelligence committee on Monday. A source told CNN Kushner's testimony would be behind closed doors.

The interest in Trump Jr. and Manafort builds on already intensive congressional investigations. In June 2016, the President's eldest son agreed to meet with someone described as a "Russian government attorney" after receiving an email offering him "very high level and sensitive information" that would "incriminate" Democratic presidential nominee Hillary Clinton, according to emails Trump Jr. publicly released last week. Manafort and Kushner attended that June 16 meeting.

Earlier this week, Sen. Dianne Feinstein, the top Democrat on the Senate judiciary committee, said that Justice Department Special Counsel Robert Mueller had signed off on the committee's request to interview Manafort and Trump Jr. in public.

Kushner's lawyer Abbe Lowell said, "As Mr. Kushner has been saying since March, he has been and is prepared to voluntarily cooperate and provide whatever information he has on the investigations to Congress. Working with and being responsive to the schedules of the committees, we have arranged Mr. Kushner's interview with the Senate for July 24. He will continue to cooperate and appreciates the opportunity to assist in putting this matter to rest."