Since the confirmation hearings for Supreme Court nominee Brett Kavanaugh started earlier this week, Sen. Cory Booker, D-NJ, has begun reading from and later publicly releasing documents that were marked "committee confidential," meaning only members of the Senate Judiciary Committee were supposed to have access to them.

Among them — which also contained documents relating to busing and affirmative action — was an email exchange between Justice Department employees under President George W. Bush that referred to San Francisco as a "mud-swamp."

Former Bush official Rachel Brand, who stepped down from her position as third-in-command at the Department of Justice earlier this year, wrote the email to Kavanaugh and two of his colleagues on Feb. 17, 2001 with the subject line "unsolicited judge recommendations." The email appears to contain a breakdown of possible nominees for circuit court judges and their partisan leanings, with conservative judges being deemed more favorable.

When it comes to a potential nominee for the Ninth Circuit whose name has been redacted, Brand had some positive things to say about the judge and some less-than positive things to say about San Francisco.

"Good libertarian/conservative," she wrote. "Smart, quick, no-nonsense. He's a flower in the mud-swamp that is SF."

The release of the documents came after Booker and Kavanaugh clashed over past statement's of Kavanaugh's that suggest he is an opponent of the legality of race-conscious programs like affirmative action, according to Vox. Booker's colleague Sen. John Cornyn, R-Texas, has threatened him with expulsion and called for an ethics investigation into the document releases.

Congressional Democrats have argued the documents don't pose a threat to national security and thus should not have been labeled "committee confidential" in the first place. Republicans also drew ire from their colleagues when they released 42,000 pages of Kavanaugh-related documents the night before the confirmation hearings were set to begin.

The full trove of documents that Booker has released so far can be viewed online here.

Filipa Ioannou is an SFGATE staff writer. Email her at fioannou@sfchronicle.com and follow her on Twitter