Ms. Cheney’s options may be obvious, but there’s no clear path ahead — and she faces the risk of inadvertently aiding Mr. Trump’s comeback.

A policy wonk with no great enthusiasm for retail politics, she could build a political operation dedicated to defeating Republicans who endorse Mr. Trump’s false claims of winning the 2020 election. That would inevitably mean openly supporting Democrats, something she has yet to commit to. On Wednesday, when asked if she believes the country would be better off under Democratic control in Washington, she dodged.

“I think we have to make sure that we are fighting against every single election denier,” she said. “The election deniers, right now, are Republicans. And I think that it shouldn’t matter what party you are. Nobody should be voting for those people, supporting them or backing them.”

Ms. Cheney also could focus on laying the groundwork for her own candidacy for president — either as a Republican or as an independent. The latter effort risks peeling away votes from Democrats and ultimately helping Mr. Trump win if he runs, as is widely expected.