Sen. Ben Sasse (R-Neb.) called on his Republican Party to rebuild itself and "repudiate the nonsense that has set our party on fire" in an in an op-ed for The Atlantic Saturday on the QAnon conspiracy theory.Why it matters: Many of the mob involved in the deadly Jan. 6 Capitol Hill riots wore items signaling their support for the far-right QAnon and a prominent member of the cult was among those arrested following the siege.Get smarter, faster with the news CEOs, entrepreneurs and top politicians read. Sign up for Axios Newsletters here. * Several Republicans who ran for Congress last year publicly supported or defended the QAnon movement or some of its tenets — something Sasee noted in his op-ed, headlined "QAnon is Destroying the GOP From Within." * Sasse blames the violence on "the blossoming of a rotten seed that took root in the Republican Party some time ago and has been nourished by treachery, poor political judgment, and cowardice."Driving the news: Sasse wrote in his op-ed that "until last week, many party leaders and consultants thought they could preach the Constitution while winking at QAnon." * "They can't," he added. "The GOP must reject conspiracy theories or be consumed by them. Now is the time to decide what this party is about." * Sasse criticized House Minority Leader Kevin McCarthy (R-Calif.) for not denouncing QAnon supporter Marjorie Taylor Greene (R-Ga.) when she was running for Congress in 2020. * "She's already announced plans to try to impeach Joe Biden on his first full day as president," Sasse wrote. "She'll keep making fools out of herself, her constituents, and the Republican Party."Worth noting: Sasse said before the House impeached President Trump for a second time he'd consider "definitely consider" any articles of impeachment against him over his conduct and comments at a rally before the riots. * The Nebraska senator criticized Trump's embrace of QAnon supporters last August, warning that Democrats could "take the Senate" this "will be a big part of why they won." * Months later, the Democrats went on to win control of the Senate.The bottom line: Sasse wrote that his party faces a choice when Trump leaves office: "We can dedicate ourselves to defending the Constitution and perpetuating our best American institutions and traditions, or we can be a party of conspiracy theories."Go deeper: * The Capitol siege's QAnon roots * House freshmen at war after Capitol siegeSupport safe, smart, sane journalism. Sign up for Axios Newsletters here.