Updated

The special counsel leading the investigation into Russia’s attempted meddling in the 2016 election wants to speak with White House staffers about Donald Trump Jr.’s controversial meeting during the campaign with a Russian lawyer, Fox News has learned.

Special Counsel Robert Mueller has requested to speak with aides involved in the president’s eldest son’s initial response to his June 2016 meeting with Russian lawyer Natalia Veselnitskaya, who promised damaging information on Democratic nominee Hillary Clinton.

Mueller has not requested to speak with the president himself, Fox News is told.

Democrats have pointed to the Trump Tower meeting to argue collusion between the Trump campaign and the Russian government during the 2016 presidential election. The Trump campaign has denied the accusations.

That Mueller would ask to speak to the individuals is "not a surprise," according to a source. It is also not viewed as "an aggressive action" on Mueller's part.

It wasn’t immediately clear with which specific aides Mueller wants to speak.

Trump Jr.’s meeting with Veselnitskaya was revealed in July.

TRUMP JR. SAYS HE WANTED TO KNOW ABOUT CLINTON'S 'FITNESS' FOR OFFICE IN RUSSIAN LAWYER MEETING

Sources told Fox News that a preliminary initial statement had been drafted by Trump Jr. and was discussed aboard Air Force One as the president was returning home from Germany. At that time, the sources said, Trump believed that the meeting was about Russian adoptions and had weighed in on the statement on that basis.

Earlier Thursday, Trump Jr. appeared before the Senate Judiciary Committee and told congressional investigators that he agreed to last year’s controversial meeting with a Russian attorney promising dirt on Hillary Clinton because he was interested in any information on the Democratic candidate’s “fitness, character or qualifications.”

In a prepared opening statement, the president’s son again denied any Russia collusion claims and sought to explain the nature of contacts he has had over the years with Russian individuals.

"I did not collude with any foreign government and do not know of anyone who did," he said.

Fox News' John Roberts contributed to this report.