Senate Minority Leader Mitch McConnell, R-Ky., announced his opposition Wednesday to a new bipartisan commission to investigate the Jan. 6 Capitol riot, saying the current congressional and criminal investigations are enough.

"There will continue to be no shortage of robust investigations by two separate branches of the federal government," McConnell said Wednesday during a floor speech in the Senate. "It’s not at all clear what new facts or additional investigation yet another commission could lay on top of the existing efforts by law enforcement and Congress."

JAN. 6 COMMISSION EXPECTED TO GET SUPPORT FROM MODERATE HOUSE REPUBLICANS, DESPITE MCCARTHY'S OPPOSITION

The House is expected to vote later Wednesday on the creation of the Jan. 6 commission, which is to be modeled after the 9/11 bipartisan panel that investigated the Sept. 11 terrorist attacks and made recommendations on how to prevent another attack.

The commission proposal in the House is authored by Homeland Security Committee Chair Bennie Thompson, D-Miss., and Ranking Member John Katko, R-N.Y.

Trump supporters try to break through a police barrier, Wednesday, Jan. 6, 2021, at the Capitol in Washington. (AP Photo/Julio Cortez)

Trump supporters try to break through a police barrier, Wednesday, Jan. 6, 2021, at the Capitol in Washington. (AP Photo/Julio Cortez)

The agreement for a commission met one major Republican demand that it includes an equal number of members from each party and requires majority approval to issue subpoenas. But it did not meet another condition that GOP Leader Kevin McCarthy and some other Republicans wanted: to investigate other political violence, such as Antifa riots, in addition to the Jan. 6 attack on the Capitol. 

MCCARTHY, REPUBLICANS OPPOSE JAN. 6 CAPITOL ATTACK COMMISSION OVER EXCLUSION OF OTHER POLITICAL VIOLENCE

"Given the political misdirections that have marred this process, given the now duplicative and potentially counterproductive nature of this effort, and given the speaker’s shortsighted scope that does not examine interrelated forms of political violence in America, I cannot support this legislation," McCarthy, R-Calif., said in a statement Tuesday. 

Supporters of President Donald Trump climb the west wall of the U.S. Capitol on Wednesday, Jan. 6, 2021, in Washington.

Supporters of President Donald Trump climb the west wall of the U.S. Capitol on Wednesday, Jan. 6, 2021, in Washington. (AP Photo/Jose Luis Magana)

While the House is expected to pass the formation of the commission later Wednesday, it was not immediately clear how many other Republicans would join McConnell in opposing the commission when it comes to a vote in the Senate.

McConnell accused Democrats of being too partisan in the formation of the commission and said he supports the investigations already underway into the Jan. 6 attack.

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"After careful consideration, I’ve made the decision to oppose the House Democrats’ slanted and unbalanced proposal for another commission to study the events of January the 6th," McConnell said. 

Senate Majority Leader Chuck Schumer, D-N.Y., said House Speaker Nancy Pelosi was "very generous" in her offer to give Republicans subpoena power and bashed GOP leadership for sabotaging the bipartisan agreement. He said it was just another example of Republicans acting beholden to former President Donald Trump, who opposed the Jan. 6 commission.

"They are caving to Donald Trump and proving that the Republican Party is still drunk off the big lie," Schumer said of Trump's insistence that he actually won the 2020 presidential election, despite courts and state election officials proving otherwise. 

Like the 9/11 Commission, the Jan. 6 panel would be a 10-person bipartisan commission. Half of the commissioners would be appointed by Democrats and the other half would be appointed by Republicans. The commission will have subpoena power to carry out the investigation but there must be bipartisan agreement by the chair and vice-chair or by a vote by a majority of commission members. 

The commission would issue a final report by Dec. 31, 2021.

Fox News' Tyler Olson contributed to this report.