This is only sort of a joke.

On Tuesday night in Missouri, the left scored one of its most lopsided wins to date in the 2018 cycle. That was the rejection of Proposition A, a ballot initiative that asked voters to weigh in on legislation enacted by disgraced former Missouri governor Eric Greitens, which would have prevented unions from collecting dues from nonmembers who are covered under union contracts. You may remember this issue from the Supreme Court’s decision in Janus v. AFSCME, in which the court held that public-sector unions could not charge fees to represented nonmembers. The law passed in Missouri would have made that standard practice for private-sector unions, too.

Opponents call such laws “right-to-work” legislation, arguing that the union’s fees are a burdensome restriction on employees. Labor unions point out that their negotiation on behalf of employees, union members or not, can be expensive. The justifiable fear for labor unions is that laws like the one signed by Greitens would reduce their ability to organize new members and, over the long term, weaken the union. That’s the fear for Democrats, too: Unions are an important part of the party’s political operation.

They showed why on Tuesday. Compare the results of the vote on Prop A — in which a “no” was a rejection of the right-to-work law — with the results of the 2016 presidential contest. Missouri is no longer a swing state in presidential politics, but on Tuesday night it looked very, very blue.

We’ve highlighted two counties that represent some of the most significant shifts from support of President Trump to rejection of a policy central to Republican politics. Jefferson is in the St. Louis suburbs; Washington, a bit farther out.

You can see how significant those shifts were on the graph below. Circles farther to the right were more supportive of Trump. Circles that are lower were more opposed to Proposition A.

Only four counties in the state backed Hillary Clinton over Trump in 2016. Only 15 of 115 support Proposition A. The lopsided result in the Prop A vote was in part a function of the largest counties rejecting it so overwhelmingly, but it was also simply a function of how broadly the proposition was opposed.

There are a number of likely reasons the proposition fared so poorly. One, to Pareene’s point, is that the question was fairly simple: Yes or no on a relatively simple question. No assessing how likable the proposition was.

More importantly, it’s not entirely incongruous to support both Trump and oppose anti-union legislation. Trump regularly claimed to have captured the affection of union members (though he was often exaggerating that effect) by criticizing trade deals and promising to focus on blue-collar America. Whether or not one views his subsequent policy moves as having fulfilled those promises, it is easy to see how that pitch might have appealed to union members in Missouri in the same way that voting against Proposition A did.

The most significant factor, though, is that this was an election in which a well-organized turnout effort could have had a significant effect. When turnout is going to be low — as is usually the case in midterm primaries — being able to mobilize voters can have an outsize effect on the results of the election. The labor movement did precisely that in Missouri, spending a lot of money and manpower to defeat the measure. Unions have built effective turnout systems and, in Missouri, that system certainly helped.

When you win by 35 points, though, it’s generally not just a function of turnout. It’s a sign that your candidate or issue was simply at odds with the electorate. That’s the real concern for Republicans in Missouri — and the real bright spot for Democrats. Even if Democrats were more mobilized to vote against Prop A than Republicans were to support it, it still got walloped.

Keep in mind that about 1.4 million votes were cast to weigh in on Proposition A. That’s more than the total votes cast in the state’s Senate primaries, where about 1.3 million votes were cast. But of those 1.3 million votes, more than half were cast by Republicans.

In other words, a lot of Republicans cast votes to protect the power of unions.

This isn’t the sort of victory that can easily translate to other places. But in a year that’s shaping up to be a good one for the Democrats electorally, it provides an additional note of warning to Republicans.

A central, long-standing policy goal of the party was put on the ballot in a red state, and it got demolished.