Sen. Cory Booker, D-N.J., threatens to release committee confidential documents during the start of day three of Brett Kavanaugh's confirmation hearing to be Associate Justice of the Supreme Court in the Senate Judiciary Committee on Thursday morning, Sept. 6, 2018.

Democratic senators, led by Cory Booker of New Jersey, released confidential documents related to Supreme Court nominee Brett Kavanaugh on Thursday over the objections of some Republicans on the Senate Judiciary Committee.

Booker, who was joined by Sens. Mazie Hirono, D-Hawaii, and Dick Durbin, D-Ill., said that he is willing to face charges that could potentially have them expelled from the Senate as a result of their actions.

The documents showing email correspondence between Kavanaugh and a number of White House officials during President George W. Bush's administration were designated "committee confidential," a label barring senators from discussing their contents in open session, NBC News reported.

Read more: Booker's 'I am Spartacus' document release wasn't as defiant as it seemed

Booker's gambit was the latest play in an ongoing struggle by Democrats to release hundreds of thousands of pages of documents related to Kavanaugh's Bush years, and while he was an attorney on the team of Kenneth Starr, who investigated President Bill Clinton in the 1990s.

But Booker had already received clearance to publicly release the documents in question before the hearing, said William Burck, a Kavanaugh ally and former co-worker who is playing a role in the document release process.

"We cleared the documents last night shortly after Senator Booker's staff asked us to," Burck told CNBC.

"I was surprised to learn about Senator Booker's histrionics this morning because we had already told him he could use the documents publicly. In fact, we have said yes to every request made by the Senate Democrats to make documents public," Burck said.

Booker had clarified his comments later at the hearing. "I broke those rules yesterday. Today, I released the documents, but they, because I shamed them," Booker said. "They didn't go through the process."

At the hearing, Sen. John Cornyn, R-Texas, accused Booker of making a political play. "Running for president is no excuse for violating the rules of the senate or of confidentiality of the documents that we are privy to," Cornyn said.

After learning that the documents were already set to be made public, Cornyn told reporters that "all this drama" was for nothing.

A spokesperson for Judiciary Chairman Chuck Grassley, R-Iowa, was not immediately available for comment. Booker's office did not immediately respond to a request for comment.

At the hearing, Booker acknowledged that doing so would violate Senate rules and could technically lead to his expulsion. "If Sen. Cornyn believes I violated senate rules, I openly invite and accept the consequences of my team releasing that email right now," he said.

Booker was quickly joined by Durbin and Hirono.

"Count me in," Durbin said. "I want to be part of this process."

Hirono chimed in a few minutes later: "I would defy anyone reading this document to be able to conclude that this should be deemed confidential in any way, shape or form."

Hirono tweet

Democrats' opening salvo Thursday echoed the raucous opening minutes of the confirmation hearings two days earlier, when Sen. Kamala Harris, D-Calif., demanded the confirmation hearings be delayed until senators had time to review Kavanaugh's paper trail.

More than 100,000 pages of documents have been blocked for public release, though lawmakers have been permitted to review them.

"This entire process has cast a cloud over Judge Kavanaugh," Sen. Dianne Feinstein, D-Calif., the top Democrat on panel, said Tuesday. "We go to these hearings under protest."

Republicans have insisted that there have been more documents released for Kavanaugh's nomination than for previous nominees.

— CNBC's Jacob Pramuk and John Schoen contributed to this report.