Some right-leaning voters who oppose Donald Trump are thinking of voting neither for him nor Kamala Harris.

I understand how they feel. In 2016, I published an article urging Never Trump conservatives to consider casting their ballot for a third-party candidate. In the election that year, I did just that.

I regret writing that column. I regret casting that vote.

To people like me, Trump represented a repudiation of everything that Ronald Reagan stood for. But as a conservative and former GOP staffer who had never voted for a Democratic presidential candidate, I harbored reservations about Hillary Clinton.

Voting for neither Trump nor Clinton seemed to be a “safe” way to express disapproval of both. Most polls at the time showed her on track to win comfortably. It seemed reasonable to argue that a significant tally for a third-party candidate might check her liberal ambitions. After all, the number of votes for Independent candidate Ross Perot in 1992 may have nudged Bill Clinton to accept bigger budget cuts than he wanted.

But the 2016 election did not go according to expectations. Despite losing the national popular vote, Trump squeaked into office by edging out Hillary Clinton in key states where polls were way off the mark.

Libertarian candidate Gary Johnson won 3% of the national vote, a high-water mark for that party. An exit poll asked his supporters whom they would choose in a two-person race. Though many said they would abstain, more picked Clinton than Trump.

We will never know whether Trump would have lost if more such voters had switched to Clinton. We do know what happened because he won. He blew up the federal debt. His incompetent handling of COVID-19 caused tens of thousands of needless deaths. He finished his term by trying to overturn an election he lost and instigating a violent rebellion against the government he had sworn to protect.

Trump turned out to be a catastrophe for our country. Hillary Clinton just was a candidate with whom I disagreed, I wish I had voted for her and encouraged others to do the same.

The next president of the United States will be Donald Trump or Kamala Harris, not anybody else. The election will almost certainly be close. We don’t have the luxury of voting third party or writing in the name of a fantasy candidate. (In most states, those write-ins won’t even count.)

Currently, many states are likely to give a lopsided margin to one candidate or the other. For example, California will probably go for Harris and West Virginia for Trump. Voters in such states might think it is OK to skip the election or vote for somebody who can’t win, thinking: “What the heck, it won’t make any difference in the electoral count, right?”

That attitude is wrong in two ways.

First, “likely” does not mean “certain.” As we have already seen, the polls can err. Never Trump folks do not want to wake up on the day after the election to find that their wasted votes have helped him score a narrow upset in their state.

Second, the popular vote matters. Under any circumstance, Trump will almost certainly refuse to accept defeat. But if he loses big in the popular vote, as well as losing the electoral vote, it will be harder for him to claim that he is the people’s choice. The larger the margin, the weaker his claim.

For us Never Trumpers, as for everybody else, the 2024 election is a binary choice.

If you abstain or vote for somebody other than Kamala Harris, you effectively vote for Trump. Consider the consequences for our country. Don’t do something you’ll regret.

John J. Pitney Jr. is a professor of American politics at Claremont McKenna College. From 1989-91, he was deputy director of research at the Republican National Committee.