US President Donald Trump's eldest son, son-in-law and ex-campaign manager are to testify before the Senate on alleged Russian meddling in the 2016 election.
Donald Trump Jr, Jared Kushner and Paul Manafort will be questioned about their links to Russian officials.
One key subject will be their meeting with a Russian lawyer last year.
Meanwhile, the president said he would not have named Jeff Sessions as attorney general if had he known he would recuse himself from the inquiry.
The president has also spoken about an until recently undisclosed conversation with Russian President Vladimir Putin at a G20 dinner, saying it was mostly "pleasantries".
The Senate, the House and a Justice Department special counsel are all investigating whether Russia interfered in the election to try to tip it in Donald Trump's favour. They are also investigating whether there was any collusion with the Trump team, which both Russia and Mr Trump have denied.
Mr Trump Jr and Mr Manafort have been called to testify before the Senate Judiciary Committee next Wednesday.
Two days earlier, Mr Kushner is to answer questions in a closed-door session of the Senate Intelligence Committee.
The hearings will be the most high-profile since sacked FBI head James Comey gave testimony in June.
The three members of Mr Trump's inner circle attended a meeting in New York in June last year with Russian lawyer Natalia Veselnitskaya after being promised damaging material on Mr Trump's election rival, Hillary Clinton.
A former Soviet counter-intelligence official, now a lobbyist, also attended the meeting,
Mr Trump Jr, who confirmed the meeting in a series of emails, said that no information on Hillary Clinton was provided.
The meeting is the firmest evidence yet of non-diplomatic interactions between Trump campaign aides and Russian figures.
On Wednesday, Ms Veselnitskaya told Russia's RT television channel she would also be willing to testify before the Senate on the matter.
Trump at six months
President Trump, in an interview with the New York Times, again defended his son's actions.
He said he had spoken to a number of senators who agreed that if they had been called and offered information on an opponent, they would have attended such a meeting.
In the same interview, Mr Trump rounded on Mr Sessions.
The attorney general recused himself from overseeing the Justice Department's Russia investigation in March, after failing to disclose at his confirmation hearing at the Senate that he had met Russia's ambassador to the US.
The president said: "How do you take a job and then recuse yourself? If he would have recused himself before the job, I would have said, 'Thanks, Jeff, but I'm not going to take you'."
Mr Sessions has not yet commented on Mr Trump's remarks.
In the same interview, Mr Trump also spoke about his conversation with Mr Putin at the G20 dinner in Germany this month.
The conversation came to light only on Tuesday, with US media reporting it lasted an hour and was "animated".
But Mr Trump said it lasted for only 15 minutes and was mostly "pleasantries".
He said the pair talked "about adoption". Russia banned Americans from adopting Russian orphans as a reaction to US measures against Russian officials accused of human rights violations.