Mitch McConnell says he will oppose confirming Judge Ketanji Brown Jackson to the Supreme Court

Senate Minority Leader Mitch McConnell said on Thursday that he will not vote to confirm Judge Ketanji Brown Jackson to serve on the U.S. Supreme Court.

While the Kentucky Republican said that he had an "open mind" going into the process, he said that after examining her "record and watching her performance this week," he "cannot and will not" back confirming her to a lifetime appointment to the high court.

Last month, President Joe Biden nominated Jackson to fill the vacancy that will arise once Justice Stephen Breyer steps down later this year.

Breyer is widely regarded as one of the court's three liberal justices. Since Jackson is expected to be a member of the court's left-leaning contingency, her addition to the court as Breyer's replacement would not shake up the court's current balance.

McConnell previously voted against confirming Jackson to serve on the U.S. Court of Appeals for the D.C. Circuit. GOP Sens. Susan Collins of Maine, Lisa Murkowski of Alaska, and Lindsey Graham of South Carolina voted in favor of confirming Jackson last year.

But even if all 50 GOP senators oppose confirming Jackson to the high court, the Senate Democratic caucus, armed with Vice President Kamala Harris's tie-breaking vote, could still elevate Jackson to the Supreme Court bench, assuming all 50 members of the Democratic caucus vote in favor of confirmation.