Wisconsin senator Ron Johnson has accused a leading Holocaust scholar of engaging in what he called “malicious poison” — criticising his rhetoric downplaying the 6 January 2021 attack on the Capitol.

       Mr Johnson, a two-term Republican who has become infamous for his embrace of conspiracy theories and quackery on subjects ranging from Covid-19 to the Capitol insurrection, attacked Emory University Professor Deborah Lipstadt at a Senate foreign relations committee hearing to confirm her nomination as the State Department’s special envoy for combatting antisemitism.

       Mr Johnson and other Republicans on the committee had worked to hold up her nomination since it was announced in July because they took umbrage at tweets she’d authored accusing Mr Johnson of promoting “white supremacy/nationalism” last year after he told a radio host that he would have feared Black Lives Matter protesters storming the Capitol more than he did the 6 January 2021 rioters.

       At the time, the Wisconsin senator said his lack of fear of pro-Trump protesters would’ve been justified because Trump voters “love this country … truly respect law enforcement, [and] would never do anything to break the law”.

       But on Tuesday, Mr Johnson hit back at the professor when it came time for him to question her after she apologised and admitted she had not been as “nuanced” as she would have preferred to be.

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       “You don’t know me. You don’t know a lot of the people you have accused online in front of millions of people,” Mr Johnson said. “You have engaged in the malicious poison [and] vile and horrible charges against people including me that you don’t even know”.

       Ms Lipstadt is expected to receive bipartisan support for her nomination.