Where should reformers focus? It’s hard to say exactly how many states and just which ones would need to adopt this reform before 2020 in order to make a difference in the outcome of the next presidential election. But as a practical matter, the race is likely to come down to only a few battlegrounds. The Cook Political Report identifies five “toss-ups”: Arizona, Florida, Michigan, Pennsylvania and Wisconsin. If ranked-choice voting were employed in these five states, but nowhere else, the Electoral College winner would be highly likely to be the same candidate who would have prevailed if a ranked-choice national popular vote were held. In fact, it’s possible that this could hold true if even a single pivotal state adopted ranked-choice voting—think Florida in the 2000 election.

Adopting ranked-choice voting in a few pivotal states won’t solve all the problems associated with the existing Electoral College system. Candidates, for instance, will continue to focus their visits and their advertising on those states perceived to be in play. But since it is impossible in the short term to conduct an actual nationwide count that ensures a majority winner, the second-best option is to produce a majority result in the pivotal states that will have the effect of mirroring what the majority result nationwide would be.

Three of the five states named by the Cook Political Report—Arizona, Florida and Michigan—could pursue this reform through a ballot initiative.