Washington — Republican Congresswoman Liz Cheney of Wyoming has been selected to serve as vice chair of the House select committee investigating the January 6 assault on the U.S. Capitol, its chairman, Democratic Congressman Bennie Thompson, announced Thursday.

“Representative Cheney has demonstrated again and again her commitment to getting answers about January 6th, ensuring accountability, and doing whatever it takes to protect democracy for the American people,” Thompson, of  Mississippi, said in a statement. “Her leadership and insights have shaped the early work of the Select Committee and this appointment underscores the bipartisan nature of this effort.”

Cheney is one of two Republicans serving on the panel, the membership of which prompted sparring between House Speaker Nancy Pelosi and Minority Leader Kevin McCarthy. While McCarthy picked five Republicans to serve on the select committee, Pelosi said in July she would be rejecting two of his selections because of comments they made about the Capitol attack.

McCarthy then pulled all five of the GOP lawmakers he wanted to name to the committee after Pelosi declined to rescind her rejection of the two lawmakers, Jim Jordan of Ohio and Jim Banks of Indiana.

Cheney was among the lawmakers appointed to the January 6 select committee by Pelosi in early July, joining seven Democrats. The speaker then tapped a second Republican, Congressman Adam Kinzinger of Illinois, for the panel following the spat with McCarthy. Both Cheney and Kinzinger voted to impeach former President Donald Trump for inciting the deadly riots at the Capitol.

Cheney said in a statement that she accepted the position of vice chair to assure the committee achieves its goal of conducting a “nonpartisan, professional and thorough investigation” into January 6.

“We owe it to the American people to investigate everything that led up to, and transpired on, January 6th,” she said. “We will not be deterred by threats or attempted obstruction and we will not rest until our task is complete.”

Nearly all House Republicans opposed the creation of the select committee to probe January 6 — only Cheney and Kinzinger voted in favor of the legislation forming the panel — and Cheney’s appointment as vice chair is likely to further inflame tensions within the GOP conference.

House Freedom Caucus Chairman Andy Biggs, a Republican from Arizona, intends to send a letter to McCarthy asking him to remove Cheney and Kinzinger from the Republican conference because they agreed to serve on the January 6 panel.

Biggs called the two “spies for the Democrats” who cannot be trusted to sit in conference meetings while GOP lawmakers plan their defense against Pelosi and other Democrats.

Maura Gillespie, Kinzinger’s spokeswoman, said in response to Biggs’ request that the committee is committed to learning the truth about the events surrounding January 6.

“When a member makes repeated calls to remove Representatives Kinzinger and Cheney from the conference, it certainly calls into question their true motives,” she said. “Especially when that member pushes conspiracy theories to their constituents and outright lies for their own personal gain.”

The committee’s probe is beginning to ramp up as it seeks records from social media companies related to claims about the 2020 presidential election and documents from eight executive branch agencies, including communications from the Trump White House, surrounding January 6.

Thompson also asked 35 social media, telecommunications and email companies to preserve information about people directly involved in the Capitol assault or who may have been involved in efforts to interfere with Congress’ tallying of state electoral votes January 6, as well as records from people “involved in organizing, funding or speaking” at rallies on January 5 and January 6, which is likely to include some Republican lawmakers.

The select committee held its first public hearing in July, during which members heard emotional testimony from four law enforcement officers who responded to the violent mob of Mr. Trump’s supporters who breached the Capitol.