In the 2012 election Gary Johnson got less than 1% of the national vote 0.99% to be exact. The Greens Jill Stein got 0.36% for a combined total of 1.35%
As of today's Real Clear Politics aggregate of polls Johnson is on 6.0% and Stein 2.20% an increase of +5.0 for Johnson and +1.84 for Stein. Their combined total increase is +6.84.
Johnson peaked at 9.2% in mid-September and has slowly been declining, as would be expected, from 9% to 8% to 7% and now 6%. Stein peaked at 4% in August and has also been declining slowly, but has been around the 2.0% to 2.60% since mid-September.
It would appear that Stein has picked up some of the ex-Sanders supporters and it may be that, as in many countries world-wide, the Greens have a support base which grows slowly but does grow.
Gary Johnson on the other hand at his 9.2% peak was clearly a vehicle for the "Never Trump's" and "Never Hillary" voters as it is doubtful in the extreme that 8% more voters had become entranced with Libertarian-ism over the last four years. I would further venture that many of those 8% would struggle to advise anything about Johnson or his platform.
In the majority of cases where a protest party has an upsurge in poll support during a campaign, it melts like the snow when election day arrives, and the "never whomever" people are faced with the prospect of the opposition party actually winning and hold their collective noses. Ross Perot is of course an obvious exception but with respect to Johnson he is no Perot in profile or resources.
I would not be surprised in the least if Johnson doesn't even get a 100% increase from 2012 to 2% which leaves around 4% of his current polling available. At this point I enter into the world of conjecture, but I venture to say that it is conjecture based on years of watching elections and in-depth reading, so here goes.
I believe that the majority of Johnson's support over 2012 are Republicans who have not been able to bring themselves to support Trump. These voters would include utterly unhappy Cruz, Jeb and supporters of the other 10-12 of Trumps primary opponents (a few like Carson have come on board). I believe that the majority of them will, facing the prospect of four years of Hillary, a leftist Supreme Court and who knows what foreign policy entanglements, will bite the bullet and vote Trump in the privacy of the polling booth.
What Johnson gets in his native New Mexico is of no interest, but in the must win states for Trump the pressure on Republicans who stated they were going to vote Johnson, will be enormous.
In Florida, Trump's most vital state, Johnson is averaging 3.4% and Stein 1.4. Clinton's poll lead average is +3.4 so the pressure on their currently declared supporters is massive.
North Carolina (Stein not on the ballot) Clinton leads by 2.5 points Johnson has 5.7%
Ohio Trump leads by 0.6 points while Johnson has 5.6% and Stein 2.0%
Nevada Clinton +4.2 points Johnson 5.5% (Stein not on ballot)
Pennsylvania Clinton +6.2 Johnson 4.8% Stein 2.6%
If in the final days Trump's polling has moved closer to Clinton both nationally and in these key states, the signal to the voters who have inflated both Johnson and Stein's number will be clear.
That is, they may well hold the absolute key to who will be elected on November 8th. They know it won't be either of Johnson or Stein but it may well be their alternate, final, choice.