On 6 September, Governor Janet Mills of Maine announced her approval of a first of its kind law that would establish ranked choice voting (RCV), which allows voters to rank their preferences rather than voting for just one candidate, for the state’s November 2020 presidential election and presidential primaries starting in 2024. Maine voters already use RCV for congressional elections and state and congressional primaries. This law will be a commonsense extension – and both major parties have good reason to embrace it.

For example, imagine that Joe Biden wins the Democratic nomination and Gabbard’s anti-intervention perspective builds support in the early primaries. Someone from the party’s base might make a run from the left. Disappointed progressives who broke with Hillary Clinton over the 1990s crime bill and her support for the Iraq war might struggle with their desire to both defeat the president and change their own party.

On the other hand, if Bernie Sanders leads the ticket, one could certainly envision a deep-pocketed centrist making a play for the center, attracting anti-Trump voters who can’t quite support a Vermont socialist.

We should be able to cast a vote that reflects our values and beliefs

If more swing states joined Maine in passing RCV, Democrats would not have to fear insurgent candidates splitting the anti-Trump vote and re-electing the president with a plurality. RCV mirrors an instant runoff: if no one reaches 50% on the first ballot, weak candidates are eliminated, and their ballots go to second choices until a candidate earns a genuine majority.

There’s plenty here for Republicans to like as well. It’s possible that conservatives like the former Ohio governor John Kasich or the former Arizona senator Jeff Flake could decide that the GOP needs to be rebuilt and rebranded beyond Trump’s image. The former congressman Joe Walsh might get enough steam in the primaries that he would want to take his case against the president to the general election. With RCV, a frustrated Republican not eager to put the Democrats back in power would be able to register his or her discontent, then perhaps rank Trump second.

It’s a tossup on which party would have benefited from RCV in 2016. Trump won 101 electoral votes from six states where he won less than half the votes. Clinton won seven states and 51 electoral votes from such states, with her margin of victory smaller than the number of votes earned by the Libertarian nominee, Gary Johnson, and the former Republican Evan McMullin in six.

It’s impossible to predict where third-party voters would have landed for a second choice. Perhaps some would have stayed home given only the selection between a Democrat and Republican. But if one assigns the Johnson and McMullin votes to Trump and the Green party votes to Clinton, Trump might have carried six more states. Where Johnson’s support came from remains an open question, but it’s one that more sensible voting rules would have answered in real time.

Quite simply, the current system is no way to run an election. Our politics suffers when voters feel browbeaten into supporting one major-party candidate simply because they hold the other in greater disdain. And candidates representing the right, left, center or independents of any stripe ought to be heard without being shouted down as spoilers.

We should be able to cast a vote that reflects our values and beliefs, if only as a form of protest. It sends an important message: a Trump re-election based entirely on second choices of disaffected Republicans would be a warning to govern differently in a second term. Likewise, a Biden win with the help of second-choice votes from progressives would send him an important signal. A frustrated third-party voter withholding a second choice would also send a message: you didn’t earn my vote.

Let’s follow Maine’s example and take ranked-choice voting for president national. This could have a major impact even if done in a handful of close swing states. Clinton won Maine by just three percentage points in 2016. Other valuable reform states where RCV could clarify outcomes include Minnesota, Michigan, Florida, Wisconsin and Pennsylvania.

Additional candidates outside the major parties are certain to join the presidential elections next year. Both parties can fear them or blame them – or they can make democracy stronger by reaching out to their supporters. The best choice should be clear to us all.