DETROIT – Most of the talk about what might happen in the presidential election this year has revolved around those swing voters who supported Barack Obama, then switched to Donald Trump.

They are certainly important – but most commentators are overlooking another category that also could be decisive:

The millions of voters who decided they couldn’t stomach either Hillary Clinton or Trump and chose third-party candidates.

The third, or minor party vote soared four years ago. Back in 2012, all minor parties combined drew only 2.2 million votes. But four years ago, that number soared to 7,922,634.

That vote made the difference in the three key states that changed parties and decided the election — Pennsylvania, Wisconsin, and most of all Michigan, where the president’s margin was tiniest – 10,704 votes out of nearly five million cast.

 In Michigan, Libertarian Party candidate Gary Johnson got 172,136 votes in 2016, while Jill Stein, nominee of the Green Party, took 51,463. Both totals were far more than the normal showing.

But what will happen this time?

Bill Gelineau, a thoughtful Libertarian Party leader from Grand Rapids, believes it depends on who the Democrats nominate.

“A lot of us think Trump is a clear and present danger,” he said. “If Democrats nominate Joe Biden – well, he is a stable and known quantity. I think a lot of us may hold their noses and vote for him.”

“But if the nominee is Bernie (Sanders) or (Elizabeth) Warren, I don’t see that happening,” he said. Though the 61-year-old Gelineau has worked for years to build up his party, he sees himself as a realist. Four years ago, their nominee, former New Mexico Gov. Gary Johnson got nearly 4.5 million votes nationwide.

“Sadly, I don’t think we can do that well again. I don’t think we are likely to have a nominee of that stature,” he said, meaning Johnson.  Gelineau himself was the Libertarian candidate for governor of Michigan in 2018; he polled a modest 56,606 votes, or 1.3 percent of the total, down considerably from the party’s high-water mark, but still better than Libertarians have done in the past.

There are two high-profile possibilities that could conceivably catch on if either wins their party’s nomination when Libertarians chose their ticket at their convention in Austin, Tex. this May.

One is Lincoln Chafee, 66, who was elected to the U.S. Senate as a Republican, later was elected governor as a Democrat, and then became first an independent and then moved to Wyoming and is now a Libertarian. He is definitely seeking the nomination.

 The other well-known potential candidate is U.S. Rep. Justin Amash, 39, a congressman from the Grand Rapids area who bolted the Republican Party last year and became an independent.

But while he has said he may seek the Libertarian nomination, Amash is thought to be more likely to run for reelection to his current seat as an independent.

Beyond those two, however, the party’s other possibilities include candidates like Baltimore’s “Vermin Supreme,” a performance artist who wears a boot on his head and pledges to make it illegal not to brush your teeth.

After the Libertarians, the other notable third party in Michigan is the Greens. Four years ago, on her second try as presidential nominee, Jill Stein became the first Green candidate since Ralph Nader to win more than a million votes nationwide.

This year, she isn’t running again. While the Greens have a large field of potential presidential candidates, the front-runners are Howie Hawkins of San Francisco, 67, who helped found the U.S. Green Party and Dario Hunter, 36, a former member of the Youngstown, Ohio board of education.

Jennifer Kurland, 38, was the Green candidate for governor of Michigan two years ago, and got 28,799 votes. Now, she is the state Green Party’s communication director. 

Though she acknowledges that this election year will “certainly be an uphill battle” for the Greens, she doesn’t share the Libertarian candidate’s belief that her party’s vote is likely to shrink.

“I don’t see this is going to be normal,” she told me. “A lot of Republicans are unhappy with Trump.”  Though the conventional wisdom is that some Green voters will desert the party in favor of a Democrat in November, she thinks Greens will get even more votes.

“I hope so!” she said when asked if the party’s nominee could outperform Stein.  The party spokesperson also said the conventional wisdom that the Greens appeal only to the left isn’t true.

Conventionally, Libertarian voters were thought to be more likely to have Republicans as their second choice; Greens, Democrats.

Maybe – and yet maybe not.

“We have some very conservative values as well,” Kurland said.  Among them: Returning taxpayer-supplied money to local communities, and allowing more decisions to be made locally.

Nor does she buy the idea the Green Party cost the Democrats the last election. “I don’t think anyone who voted for Jill Stein last time would have voted for Hillary Clinton,” she said.

Perhaps.  What we do know is that in recent years, people often have gone to the polls and defied expectations. How or if they will do so this year remains to be seen.        

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 (Editor’s Note: A version of this column also appeared in the Toledo Blade.)