The politician who may help determine the winner of the presidential election travels without an entourage, flies coach and browses Yelp when he needs to find a place to grab a quick bite to eat between campaign stops.

Gary Johnson, the Libertarian Party’s candidate for president, will be on the presidential ballot in all 50 states, the first time a third-party candidate has managed that feat in 20 years. And if current polls hold true — they have him in the high single digits — he may be on track to win more votes than any third-party peer since the Texas billionaire Ross Perot ran as an independent in 1992.

But Mr. Johnson, a 63-year-old former governor of New Mexico, is walking a lonely road. While his name may be familiar, his face is not: He is rarely recognized as he hustles through airport taxi lines, wheeling his own luggage.

Last week, he missed the chance to make his case to more than 80 million Americans, when he fell shy of the 15 percent polling average needed for inclusion in the first presidential debate. Even his running mate, William Weld, a former Republican governor of Massachusetts, has been playing down the strength of their ticket, saying that he is not sure anyone is more qualified to be president than Hillary Clinton, the Democratic nominee.