Spoiler Alert !!! Cheney running for President will not stop Trump! At best, she would attract a pathetically small group of people who wouldn't have voted for Trump anyway.
Bottom line: Cheney running for President would not take 1 vote from Trump.
Liz Cheney has Pierre Delecto's vote. She has Evan McMuffin's vote. She has Bill Kristol's vote. She has Mary Trump's vote. It's a start, and she's building momentum.