Senate Majority Leader Mitch McConnell (R-Ky.) said in an interview that aired Friday that Sen. Cory Booker (D-N.J.) could face scrutiny from the Senate Ethics Committee for violating a rule that prohibits the release of confidential material.

During Thursday’s hearing on the nomination of Judge Brett M. Kavanaugh to the Supreme Court, Booker said he was knowingly violating a Senate rule by releasing an email revealing the nominee’s views on racial profiling. After another senator on the Judiciary Committee said that could result in expulsion, Booker dared his colleagues to take that action.

It turns out that document had already been cleared for public release. But later Thursday afternoon, Booker, who is weighing a 2020 presidential bid, released what he said were 28 documents marked “committee confidential” in a defiant bid to make the confirmation process more transparent.

During a radio interview, McConnell characterized Booker’s actions as “unusual behavior” and said it “wouldn’t surprise me” if it draws the attention of the Ethics Committee.

“When you break the Senate rules, it’s something the Ethics Committee could take a look at,” McConnell told host Hugh Hewitt. “And that would be up to them to decide. But it’s routinely looked at by the Ethics Committee.”

Asked by Hewitt if he would “support that being done expeditiously,” McConnell said it’s not his job to order the committee to take action.

“But they have an obligation to look into violations of the Senate rules, and it wouldn’t surprise me if they did,” McConnell said.

During the hearing, Sen. John Cornyn (R-Tex.) read a Senate rule that states that the release of confidential material can lead to expulsion and called Booker’s behavior “outrageous.”

“I knowingly violated the rules that were put forth,” Booker responded. “I come from a long line, as all of us do as Americans, of understanding what that kind of civil disobedience is, and I understand the consequences.”

No senator has been expelled from the chamber since 1862.

In a tweet Friday, Cornyn, the No. 2 Republican in the Senate, called Booker’s actions “likely a matter for the Senate Ethics Committee.”

Booker responded with several tweets, saying he stood by his actions and plans to make public more “committee confidential” documents later Friday to combat what he called a “sham process.”

During the radio interview, McConnell said he has no doubt that Kavanaugh will be confirmed by the end of the month and join the high court for its new term in October.

“None whatsoever,” McConnell told Hewitt. “I think any doubts anybody might have had have been dispelled by his virtuoso performance before the Judiciary Committee. I mean, it’s stunning. He’s just a stellar nomination in every respect.”

Seung Min Kim contributed to this report.