The Republican challenging Liz Cheney for a leadership role in the party on Thursday repeated Donald Trump’s false claims that the 2020 election remains in doubt, in a sign of how loyalty to the former president has become the litmus test for advancement within the caucus.

Elise Stefanik, a 36-year-old from New York, is jockeying to be elected the next Republican conference chair in the House of Representatives amid calls to remove Cheney from the post over her outspoken refusal to accept claims that the election was stolen.

Trump on Wednesday endorsed Stefanik for the role, which would make her the party’s most senior woman on Capitol Hill, calling her a “tough and smart communicator”. He attacked Cheney as “a warmongering fool who has no business in Republican party leadership”, in a statement issued by his Save America political action committee.