IN RESPONSE to Donald Trump redoubling his attack on America’s 11m-odd illegal immigrants and their progeny, Gary Johnson, who is vying to pick up Republican voters repelled by Mr Trump, refused even to describe them as “illegal”. “If you use the term “illegal immigrants”, that is very incendiary to our Hispanic population here in this country,” said the former governor of New Mexico and presidential nominee of the Libertarian Party. He preferred the term “undocumented workers”, and added that, in their shoes, he would be one too: “They came into this country because they couldn’t get in legally and the jobs existed and you or I would have done the same thing.”

Formerly a Republican, Mr Johnson is saying what a lot of his former party colleagues would like to about Mr Trump’s thuggery. How John McCain, Marco Rubio, Scott Walker and other moderate Republicans—all sometime or current supporters of immigration reform—must wish they were free, or brave enough, to echo him.

Likeminded Republicans represent a big electoral opportunity for Mr Johnson, who won just 0.99% of the vote for the Libertarians in the 2012 presidential election. So do the many Democrats unenthused by their nominee, Hillary Clinton. In the minority of national polls that name him as an alternative to Mr Trump and Mrs Clinton, he gets around 8% of the vote, including disgruntled Republicans and Democrats in similar measure. (Jill Stein, the Greens’ candidate, is running at around 3%.)

That is big for the Libertarians. This late in the race—there are only 10 weeks until the election—third-party candidates typically start to fade. Mr Johnson’s tally, as a proliferating number of polls have shown, has been holding steady for weeks. It is higher, by one reckoning, than that of any other third-party candidate, at this point in the campaign, since 1948. At the least, Mr Johnson appears to be on course to pull off the best result for a third-party candidate since Ralph Nader, standing for the Green Party, won 3% of the vote in 2000.

Non-partisan Americans of many shades will be cheered by this. Mr Johnson styles himself a fiscal conservative and a social liberal. He hates regulation and taxes and wants people to be free to marry whomever and smoke whatever they want. He gave up the spliffs himself some years ago, but swears by the marijuana pills he consumed to cope with the pain of his injuries from a paragliding accident.

There is a lot to like about him personally, too. At a time when the main anti-politics candidate, Mr Trump, is more sick with self-love than any preening politico, Mr Johnson is admirably down-to-earth. “This is a crazy election,” he said at a recent campaign event. “You know how crazy this election is? I’m going to be the next president of the United States. That’s how crazy!”

The trouble for Mr Johnson is that, to most American political tastes, he actually is quite crazy. The sort of cautious, orthodox conservative that Mr Trump has repelled tends to be wary of dope-smokers. National security hawks, another conservative type that loathes the braggart tycoon, are meanwhile unimpressed by Mr Johnson’s extreme aversion to military intervention. Disgruntled supporters of Senator Bernie Sanders, Mrs Clinton’s opponent in the primaries—for whom Mr Johnson has expressed admiration—struggle to embrace a man who is opposed to putting a price on greenhouse gases and calls taxation a “plague”.

The loathing of most Democrats and Republicans for each other’s candidates is another factor working against Mr Johnson. It will make turnout for the two big parties much higher than it might otherwise be, preserving the two-party system in a lacquer of mutual detestation. Hence Mr Johnson, despite his joshing optimism about his prospects, is not kicking on as he had hoped to.

For that to happen, as he himself has repeatedly said, he must figure in the three televised presidential debates scheduled to take place in last September and October. To qualify, he would need, over the next two weeks, to raise his support to an average of 15% in a suite of polls. It is hard to imagine that happening.