After the eldest son of President Donald Trump admitted that he met with a lawyer with connections to the Russian government during his father’s campaign last year, he affirmed on Monday that he would cooperate with the Senate committee investigating whether the campaign colluded in Russia’s interference in last year’s election.

“Happy to work with the committee to pass on what I know,” Donald Trump Jr. said on Twitter.

Happy to work with the committee to pass on what I know. https://t.co/tL47NOoteM — Donald Trump Jr. (@DonaldJTrumpJr) July 10, 2017

Earlier in the day, Sen. Susan Collins (R-Maine), a member of the Senate intelligence committee, which is leading one of several investigations into the Trump campaign’s ties to Russia, called on the committee to speak to the younger Trump, as well as to then-campaign-chairman Paul Manafort and Trump’s son-in-law and adviser Jared Kushner, who were also present at the meeting.

“Our intelligence committee needs to interview him and others who attended the meeting,” Collins told reporters on Capitol Hill, after the New York Times reported that Trump Jr. met with the Kremlin-linked lawyer in June of 2016, after being promised damaging information on his father’s opponent, Hillary Clinton.

The committee is interested in interviewing Trump Jr. as part of its investigation, a committee source told NBC News.

But a spokesperson for Sen. Richard Burr (R-N.C.), the committee’s chairman, would not confirm the report.

When asked by reporters on Capitol Hill, Sen. Mark Warner (D-Va.), the committee’s vice chair, said Monday afternoon that he would “absolutely” want to speak to Trump Jr. as part of the committee’s efforts.

But when pressed further, he would not confirm whether the committee would formally ask the younger Trump for an interview.

“I’m not going to get into the witness list,” he said. “But rest assured that Donald Trump Jr. is somebody we want to talk to.”

The Senate intelligence committee has reportedly also requested an interview with Kushner as part of its probe. It also featured high-profile public testimony from fired FBI director James Comey and Attorney General Jeff Sessions last month.

Also investigating ties between the Trump campaign and Russia are the House intelligence committee and an independent probe led by special counsel Robert Mueller. Mueller’s team is also investigating whether Trump obstructed justice.

This article has been updated with comments from Warner.