Most Americans don’t know who Gary Johnson is. Of those that do, most probably have a vague sense of him as “the pot guy” or, at a push, “the libertarian”. As the Republican Governor of New Mexico, a position he held for two terms from 1995 to 2003, he ran a fiscally conservative administration and argued for marijuana legalisation. He is still the highest-ranked elected official to have done so. He also claims to have vetoed more legislation than his 49 contemporary governors combined. He is in Orlando to ask the Libertarians to make him their candidate for the presidency.

In 2011 he dipped his toe into the race for the Republican candidacy. When he didn’t get very far he sought, and won, the Libertarian nomination. As their candidate, he received just under one per cent of the national vote. His own bar for success was five per cent — a level of support which would give the Libertarians “major party” status, an important regulatory distinction — but his 1.27 million votes was still a record number for the party and more than the sum of the votes for all other minor parties.

For a man who wants to be President of the United States, Gary Johnson apologises a lot — often when he doesn’t have anything to apologise for. Apologetic modesty is his default setting. When answering questions, even easy ones, he is prone to raise his shoulders in a shrug, tilt his head, smile and begin his answer with “Look . . .”, “Listen . . .”, “Well . . .” or some other I’m-being-as-reasonable-as-I-can sort of opening. When he complains about not being included in national polls, a regular gripe of his, he does not rail at being shut out of the system; instead, he says calmly, “Hey, why not include this guy?” At one point in the convention he even says, “I constantly apologise for not being the best advocate when it comes to articulating these things.” His style, however, is a mixed blessing. The bumbling means media appearances can fall flat and he often misses opportunities to make a clear case for libertarianism. But by avoiding the kind of declarative statements that go down well with doctrinaire libertarians — “Taxation is theft!” — he has an appeal to voters susceptible to libertarianism of a more common-sense tinge. Added to Johnson’s mild manner is a lack of polish. During one televised press conference in Orlando, a journalist asks how he feels and he releases a loud “Whooooooop!” When asked if he’s a fringe candidate his response is usually “Oh, yeah, totally fringe.” The last time he ran for president he stripped naked and climbed into a hot tub while a reporter profiling him looked on.

Johnson spent his life before politics running Big J Enterprises, a thousand-man construction company that grew out of his work as a door-to-door handyman in college. He is lean and fit, not just by the standards of a 63-year-old but by any measure. In his spare time he runs ultramarathons and takes part in Ironman races (extended triathlons). He has climbed Everest and hasn’t had a drink in 29 years because alcohol was “stopping me being the best rock climber I could be”. He has spent the last few years as CEO of a medical marijuana company and said in March that he uses the drug “occasionally”.