This was supposed to be the year the Libertarian Party went mainstream. Given the two historically unpopular major party candidates and with a former governor, Gary Johnson, as their nominee, things were looking good for the Libertarians. Johnson made it onto the ballot in all 50 states. He was regularly polling in the low double digits, and his support held up after the Democratic and Republican parties’ conventions — past the point when most third-party candidates begin to fade.

Things, however, have taken a turn for the worse for Johnson. His numbers are dropping — from about 9 percent in national polls in August to 6 percent now — and he’s been overshadowed by another (and previously even more obscure) third-party candidate.

Johnson’s decline isn’t shocking. Third-party candidates usually lose steam the closer we get to the election. But Johnson is faltering even against that standard. Based on his polling in late August, FiveThirtyEight’s polls-plus model, which accounts for the drop-off third-party candidates usually experience, projected Johnson to get around 7 percent of the vote. The same model has him down to just 5.6 percent now.

What went wrong? You could point to Johnson’s missing the debates. He has lost about 1.5 percentage points from his national poll numbers since late September (when the first debate took place). However, he may have already been on a downward trajectory before the debates took place; on Sept. 25, the day before the first debate, he had 7.3 percent, on average, in national polls, compared with 9 percent a month before. So, it’s quite possible Johnson’s numbers would have continued to dip even if he appeared on the debate stage. Johnson, of course, has committed some policy-related gaffes — not knowing basic facts about the Syrian War or being able to name a foreign leader he admires — that suggest perhaps the debates would have been rough on him.

Another plausible explanation is that Johnson was simply a “protest” choice. Perhaps many voters who said they were going to vote for him weren’t really interested in Johnson specifically but were merely voicing frustration with Donald Trump and Hillary Clinton instead. There’s evidence for this. In August, when Johnson was flying high, a majority of voters had no opinion of him. In addition, many younger voters who as a group voted heavily for Sen. Bernie Sanders in the Democratic primary said they were going to vote for Johnson, even though Johnson and Sanders have very different ideologies. That seemed at least a little unsustainable. Indeed, as the campaign has taken shape and Sanders stumps for Clinton, Johnson’s numbers seem to be falling with young voters as Clinton’s rise.

But it’s not just nationally where Johnson is taking a hit. Johnson had particularly hoped to do well in Utah and even placed his campaign headquarters there. That’s because Republican-leaning Mormons make up the majority of the state’s population and don’t like Trump, as illustrated by his poor performance in the Utah caucuses. The idea was that maybe Johnson could convince these anti-Trump Republicans to back his bid. Back in late August, in fact, Johnson was well above his national numbers in Utah, with about 13 percent of the vote in the state in our polls-only forecast.

That same forecast shows Johnson with less than 8 percent in Utah now, and he had just 5 percent in three Utah polls released in the last week. Blame independent Evan McMullin. McMullin entered the race for president late, as a choice for anti-Trump conservatives. He’s also a Mormon who was born in Utah. McMullin has momentum in the Utah polls and is now up to 26 percent of the vote in the polls-only model. He even led in the most recent survey of the state.

The only real question for the rest of Johnson’s campaign is how much more ground, if any, will he lose? As long as Johnson doesn’t dip below 5 percent, he’ll qualify the Libertarian Party for federal funding in 2020. That still looks like it’s probably going to happen. And while that might not be the most glorious ending, it’s still a better ending nationally than any other third-party candidate for president since 1996.