The bottom is falling out of Gary Johnson’s poll numbers.

The two-time Libertarian presidential candidate has shed roughly half his supporters over the past two months. His slide from nearly 10 percent in September to a recent polling average of 5.6 percent — combined with Hillary Clinton’s growing advantage over Donald Trump — means Johnson is increasingly unlikely to be a major factor unless the race tightens in the final two weeks.


The former New Mexico governor, along with other third-party candidates, could still tip the scales in states where minor-party candidates have traditionally run strongest. But despite Johnson’s large national profile, the third-party candidate who now has the best chance of swinging a state result is Evan McMullin — the former House GOP staffer running as an independent who is climbing in the polls in Utah, typically a safe Republican state.

But McMullin is on the ballot in only about a dozen states, while Johnson is on the ballot in all 50 states plus the District of Columbia and Green Party nominee Jill Stein is on 45 ballots, including D.C.

In recent presidential elections, third-party candidates have been kept in the low single-digits on Election Day. At the national level, 1.7 percent of voters in 2012 chose a candidate from outside the two major-party nominees, up from 1.4 percent in 2008 and 1 percent in 2004. In 2000, when Ralph Nader won 2.7 percent of the vote as the Green Party nominee, 3.7 percent of voters picked from outside the Democratic and Republican candidates.

Despite the fact his poll numbers are twice Nader’s 2000 vote share, Johnson is not assured of earning a larger percentage than the longtime consumer-rights advocate, who appeared to siphon votes away from Al Gore to tilt Florida and New Hampshire to George W. Bush. (The 2000 election was much tighter nationally than this year’s race projects to be: Gore finished about a half-point above Bush in the popular vote.)

Why might Johnson continue to fade? First, his trajectory has been steadily downward over the past two months, especially he failed to qualify for the presidential debates.

At the start of September, Johnson was at 9.2 percent in the national polls. By mid-September, when the nonpartisan commission that administers the debates ruled Johnson failed to reach the 15 percent threshold, he was at 8.4 percent. And when it came time to apply the cut for the final debate two weeks ago, Johnson was at 7 percent.

Since then, he has continued to plummet. Johnson is at 5 percent in the most recent ABC News/Washington Post tracking poll, conducted last Thursday through Sunday. And in a CNN/ORC International poll conducted over the same time period, he fell to just 3 percent, down from 7 percent three weeks prior.

Part of Johnson’s autumn decline has been a result of major national pollsters switching from surveys of registered voters to those of likely voters. In that CNN/ORC poll this past weekend, Johnson was at 5 percent among all registered voters but fell to 3 percent among likely voters.

That’s probably not just a polling illusion: In general, supporters of third-party candidates say they are less likely to turn out on Election Day.

That’s one reason why, in most elections, third-party candidates underperform their polling numbers in the final vote count. The exception to the rule? Ross Perot in 1992, who earned nearly 19 percent of the vote despite running 5 to 10 points lower in the polls before the election.

Johnson, given his current trajectory, seems unlikely to replicate Perot’s late surge. But that doesn’t mean he can’t have an impact — especially in states where his polling numbers have been more durable and where third-party candidates have run stronger in recent election cycles.

One of them would be Colorado, where third-party candidates have won 2.8 percent of the vote in the past four presidential elections, and Trump is still making a play to close the gap in the polls there. Johnson was at 10 percent in a Quinnipiac University poll earlier this month that showed Clinton ahead by 8 points.

Clinton has also opened up a lead in Nevada, which has given 2.4 percent of the vote to third-party candidates since 2000. She was 7 points in front of Trump in a Las Vegas Review-Journal poll last week. That poll showed Johnson at 6 percent — a share that could become more pivotal if the race tightens again. Moreover, while Stein isn’t on the ballot there, voters in Nevada also have the unique option to choose the ballot line “None of these candidates.”

In New Hampshire, Nader won 3.9 percent of the vote in 2000, while Bush outpaced Gore by 1.3 points — and the state has given third-party candidates 2.1 percent of the vote over the past four elections combined. While Clinton is 8 points ahead of Trump in the latest RealClearPolitics average in New Hampshire, Johnson is at 9.5 percent and could play a significant role in a tighter election.

If the race doesn’t tighten, Johnson could tip the balance in a number of traditionally Republican states that could go Democratic this year.

Utah is the state most likely to swing based on support for third-party candidates. McMullin — the Utah-born, Mormon Republican-turned-independent who’s on the ballot in 11 states — is running roughly even with Clinton in his home state. And both Clinton and McMullin are closing in on Trump, putting the state’s six electoral votes in play. Johnson, meanwhile, is at 7.5 percent in the RealClearPolitics average in Utah, though the most recent polls that comprise the average show him sliding to about 5 percent.

Upcoming Johnson events provide a window into where the campaign is playing. The candidate will be in South Dakota on Wednesday; a Mason-Dixon poll last week found Johnson at 7 percent there, equal to Trump’s lead over Clinton. On Thursday, he’ll travel to Minnesota, where another Mason-Dixon poll has Johnson at 6 percent and Clinton leading Trump by 8 points.

Johnson is headed to more traditional battleground states for the weekend: Michigan on Friday and Ohio on Saturday. Both states have lagged the national average in voting for third-party candidates over the past four elections — 1.5 percent and 1.7 percent, respectively — but Johnson’s numbers have held up well in Michigan, where he is at 7.5 percent in the latest RealClearPolitics average. He’s at 5.3 percent in Ohio, but Trump and Clinton are essentially deadlocked there.

Johnson’s running mate, meanwhile, is venturing up to perhaps the campaign’s best hope to win a large share of the vote: Alaska. Former Massachusetts Gov. William Weld will be in Anchorage on Thursday.

Reliable polling is sparse in Alaska, but the remote state has given a much larger share of its votes in the past four presidential elections, 5.9 percent, to third-party candidates. That’s nearly 4 points larger than the national average, and well above the next-closest state: Montana, at 4.1 percent.

