“You called this Brexit thing right. Who do you think will be our next president?” I was asked the question several times at the Republican Convention in Cleveland last week, and I eventually got my answer pat.

“Your next president will be a 70-year-old New Yorker who is not a natural blond – and who is unfit for office”.

How easily those three words slide from the tongue. Unfit for office. Politicians deal in exaggeration, and the phrase has become almost trite. But I was using it quite deliberately. With 230 million eligible American adults to choose from, the two big parties have both managed to pick candidates who would disgrace the White House.

Unfit for office. The words don’t mean “disagrees with me”. It’s your character that makes you unfit, not your policies.

The one thing we should look for in an aspirant president is a recognition that the job is bigger than its occupant. Leading the free world is a role that should simultaneously humble and exalt. That both Hillary Clinton and Donald Trump regard the presidency as a bauble, a plaything, is disqualification enough.

American conservatives fall into two categories. Those who will sit this election out, or vote for a third party candidate (usually Gary Johnson of the Libertarian Party); and those who will reluctantly back Trump because they see him as the best way to stop Hillary, who they fear will pack the Supreme Court.

I am with the first camp. When someone is unfit for office, it really doesn’t matter who the opposition is. It’s not a question of whether X is less fit than Y. Both are unfit. If you’re in any doubt, read for yourself Donald Trump’s ranting response when Ted Cruz, whom he had insulted throughout the Republican primary, failed to endorse him.

Even on the narrow issue of the Supreme Court, I don’t see how the Donald would be any less dangerous, from a conservative perspective, than his opponent. This is a man who sees it as the job of the President, rather than the judiciary, to mandate the death sentence for people who murder police officers; who wants Muslims to register with the state, regardless of the Fifth Amendment; who demands that critical journalists be sacked, and wants to change the libel laws to tilt the balance against them; who gleefully speculated that, if elected, he would take revenge on a judge who had failed to rule his way in a class action lawsuit involving alleged fraud by Trump University.

When he was asked on Twitter by Senator Ben Sasse of Nebraska “Will you commit to rolling back Exec power & undoing Obama unilateral habit? These r sincere questions & I sincerely hope u answer rather than insult,” Trump replied, “@BenSasse looks more like a gym rat than a U.S. Senator. How the hell did he ever get elected?”

I’ll say it one more time. Unfit for office. Each party has put forward the most disliked, distrusted and disreputable candidate it could find (though, in fairness, the GOP was the subject of a hostile takeover). If I were American, I’d return the compliment by refusing to support either.

There’s a classic early Simpsons episode where two alien invaders, Kang and Kodos, run for the presidency, both promising to enslave the human race. When someone suggests supporting a third party candidate, the two reptilians reply in mocking unison “Go ahead – waste your vote!”

No. The only wasted vote is a vote cast without conviction.