Sen. Chuck Grassley, R-Iowa, said he wants Trump Jr.to testify "pretty soon", and it could be as early as next week.
"Mr. Manafort must answer questions about his deeply disturbing - and possibly criminal - conduct throughout the campaign, including recent revelations that he joined a meeting with President Trump's son and a Russian agent to seek "dirt" on Hilary Clinton", Blumenthal said in a written statement.
Manafort also sat in on the meeting with Russian attorney Natalia Veselnitskaya, described as a "Russian government attorney" by the go-between, Rob Goldstone, who told Donald Trump Jr of the Kremlin's plans.
A former assistant attorney general overseeing the criminal division under President George W. Bush, Wray now works as a criminal defense lawyer based in Washington, D.C. Yet she was able to meet with Trump Jr.at Trump Tower in June. He said he was willing to subpoena him if he refused to testify.
The Senate Judiciary Committee is one of several congressional committees investigating Russian meddling in the US election.
"Happy to work with the committee to pass on what I know", Trump Jr., said in a tweet responding to a call from Republican Senator and member of the investigative panel Susan Collins that he be interviewed as part of the probe.
"I think it's just raised a lot of questions. but the real way that I feel comfortable inviting him is ever since President Trump was elected", Grassley said Thursday.
Tuesday morning, Trump Jr. posted an email chain on his Twitter account documenting the arrangement.
USA intelligence agencies have blamed the Russian government for meddling through hacking in last year's election to benefit Trump and harm Hillary Clinton, his Democratic opponent. Trump Jr. said the meeting "really went nowhere" and that he never told his father about it because there was "nothing to tell".
House of Representatives Minority Leader Nancy Pelosi claimed on Tuesday that the meeting between Trump Jr., Jared Kushner, Manafort and Veselnitskaya is a "grave development" in the investigation of possible collusion between Russian Federation and the Trump campaign.
Investigations into possible collusion between Russian Federation and the Trump campaign have shadowed the White House for months.