BOSTON — Sen. Jeff Flake said Monday he was working with the White House counsel's office to ensure that the FBI is able to do a "real investigation" into allegations of sexual misconduct against Supreme Court nominee Brett Kavanaugh.

"We certainly want the FBI to do a real investigation and we are working to make sure that happens. I've had discussions, many yesterday, with my colleagues, with the White House counsel's office, my staff is following up as well. I had one of those conversations just five minutes ago to make sure that the — that any current credible allegation that has been made has been fully investigated," he said at the Forbes' Under 30 Summit.

"It does no good to have an investigation that just gives us more cover for example. We actually need to find out what we can find out," he continued, adding that "we have to realize that we may not be able to find out everything."

Flake's comments came as a senior U.S. official and a separate source confirmed to NBC News on Monday that the White House has authorized the FBI to expand its initially limited investigation into sexual misconduct allegations against Kavanaugh by interviewing anyone it deems necessary as long as the review is finished by the end of the week. The New York Times first reported the change in the scope.

President Donald Trump also said Monday that he thinks "the FBI should interview anybody that they want within reason, but you have to stay within reason."

Flake's push for an aggressive investigation followed after last week's intense hearings on Capitol Hill that culminated with Flake siding with his Democratic colleagues in seeking a one-week pause on the confirmation process of Kavanaugh to allow the FBI to investigate multiple claims of sexual misconduct.

Over the weekend, Flake was called a "hero" at the MSNBC Global Citizen Festival when he came out on stage with friend and Democratic colleague, Sen. Chris Coons of Delaware. But here in Boston, protesters gathered outside the Forbes Under 30 Summit where Flake was speaking to decry Kavanaugh's nomination and the allegations against him.