She will not abstain.
She will not vote for the Libertarian or any other minor party candidate.
She will not write in some Republican she approves.
She explains why not.
Per the blurb at the bottom of the Politico article, this is the author.
Kori Schake is a fellow at the Hoover Institution.
She was the director for defense strategy and requirements on the National Security Council staff, and deputy director for policy planning in the State Department of the George W. Bush administration.
This is her piece.
How Brexit convinced me to vote for Hillary
I was planning to cast a protest vote in November: write in Mitch Daniels or one of my terrific nephews, and vote Republican down-ballot to support strong Republican voices in Congress and help rebuild the party in the long run.
But that approach is only satisfactory if Trump has no chance of winning.
I’m genuinely concerned now that Trump could get elected, and that is why I’m voting for Hillary Clinton.
. . . .
Presidential contests are two-person races in the United States, and the only candidates who have a serious prospect of victory are the party standard-bearers.
Protest votes are more satisfying than voting for the lesser of two evils, but they could result in Donald Trump being elected, just as British protest votes created an outcome many who cast those ballots realized, only too late, they never wanted at all.
Republican women organize for Hillary
Republicans should embrace a Hillary Clinton presidency