FLORENCE, Italy — This Sunday, Italians will go to the polls to elect — they hope — a new government. I’ve been spending the past year in Italy, and it seems like the election here is a funhouse mirror version of the US election in 2016. And that, I think, tells us something about America.

For all the differences between the American and Italian experience, the main one is in the way governing coalitions are formed. We would understand US politics better if we paid attention to that.

Similarities between the 2018 Italian election and the 2016 US election begin with the moderate left party, currently leading the government. This party, headed by Matteo Renzi, even has a familiar name: the Partito Democratico, or Democratic Party. And as with the Democratic Party in America, many of its allies view it as too centrist, and some are defecting to minor parties to its left.

Meanwhile, the main opposition has been steadily moving to the right. In this election, it is a coalition of right-leaning parties, including Silvio Berlusconi’s Forza Italia (Go Italy), which is being pulled further right by Matteo Salvini’s anti-immigrant and populist La Lega (formerly “La Lega Nord,” or the Northern League) and Giorgia Meloni’s similar Fratelli d’Italia (Brothers of Italy).

The Italian election even has an anti-party populist challenge, from the Movimento Cinque Stelle (Five Star Movement), which sometimes seems like what would happen if you put Bernie Sanders, Donald Trump, and Jon Stewart in a blender. M5S was formed by a comedian, and its most consistent position is that it doesn’t want anything to do with the establishment. The big difference from the United States, then, is that this populist movement is separate from the left and right parties. It’s a big-tent coalition of extremists of any stripe.

There are surely several reasons why similar impulses are expressing themselves differently in Italy, but one has to be that the US system is aggressively a two-party system. Our electoral and governing institutions discourage successful third parties. So an anti-establishment populist movement will be most effective if it works within an existing party, as Sanders and Trump both demonstrate. This is the strategy that the populist Lega is pursuing. But that wouldn’t be an option for a movement that tries to bridge left and right anti-establishment attitudes, so populism of that form doesn’t thrive in US elections.

The M5S actively eschews coalitions. The new Italian system, in use for the first time in this election, is meant to encourage them. The ballot allows the center left and the center right to pool the votes from across their coalitions when determining strength. According to recent polls, M5S will likely win more votes than any other single party, but not more than the center-right coalition. And no one would win enough to form a government outright, so even a third-place center left may have a role to play.

Several scenarios are possible. The establishment Partito Democratico and Forza Italia may try to form a grand coalition to block out the anti-establishment populists. Such a coalition may or may not need to include other parties. Alternatively, the populists Lega and M5S might have enough to form a coalition if the latter will agree to share power. The point is, even once the votes are tallied, it’s not clear who will be in government.

These are concerns our majoritarian and presidential system never even notices. In a two-party system, the governing coalition is effectively determined before the election, through the selection of the party leaders. The 2016 election offered the choice of a Trump-led government or a Clinton-led government. In a multi-party parliamentary system, some negotiating will usually take place after the election. The Italian system tries to simplify this for voters, with formally established pre-electoral coalitions, but even they may not be able to form a government.

This is not a unique phenomenon. Every parliamentary system has the potential to form a coalition government, and there is nothing wrong with coalitions. What makes the Italian situation seem so dramatic is merely that the three main players have huge disagreements among them. Polarization in Italian politics is multidimensional.

All this has two implications, I think, for American politics.

The first is that one factor behind Trump’s inability to work with the Republican Party is partly the fact that the party is a coalition of interests that are held together by our system. The conservative ideology goes a long way toward defining this coalition. And polarization helps drive the factions on the right into each other’s arms. But the conservative coalition still has fissures; Trump amplifies some elements and diminishes others. He also has no experience working with a coalition, so he doesn’t know how to hold it together.

In a multi-party system, each faction can have its own leader. This can create its own issues: Who “leads” the center right in Italy? Salvini? Berlusconi? (Or, since Berlusconi is currently barred from holding office, someone else from FI?) But the factions themselves are easier to identify. Just because the factions are sometimes masked in the United States doesn’t mean they aren’t there.

The second implication is that ballot reformers in the United States would do well to think about the government formation stage. Some talk of the tyranny of the two-party system, but much of what is happening is the interplay of our party system and our presidential system. Even if voters had more options on the ballot, there would be only one presidential winner.

If we want to select leaders who proportionally reflect the support of different parties, we’d need other reforms as well. There are ways to do this, from fusion parties, in which multiple parties endorse the same candidate, to an outright parliamentary system. But you rarely see this part of the story on the agenda. Italy’s exciting election reminds us that we should.