Larry Diamond in The American Interest:
The most promising change is ranked choice voting, sometimes called “the instant runoff.” Imagine that Arizona’s voters had serious options beyond a Democrat and a Republican, and that instead of voting for a single Senate candidate in the general election, voters could rank their choices one, two, three, and so on. Under ranked choice voting, if no candidate gets a majority of first place votes, the candidate with the lowest number of such votes is eliminated, and his or her votes are redistributed to their voters’ second choices. The process continues until someone gets a majority or a final-round plurality. The instant run-off has the potential to lower the temperature of political polarization, by enabling voters to opt for an independent or third-party candidate without fear that in doing so they will “waste” their vote and thus help elect the candidate they dislike the most.
What if Arizona had ranked choice voting? Flake could have made his clarion call on the Senate floor and then announced that he was running as an independent. Corker could have done the same in Tennessee. Under ranked choice voting, each might have had a decent chance of winning. Indeed, Alaska Senator Lisa Murkowski did (just barely) win re-election as an independent in the 2010 general election after losing the Republican primary to a Tea Party candidate. But she had to mount a heroic and improbable write-in campaign because of the “sore loser” rule, which (in 45 states) prevents a candidate from getting on the ballot in the general election if he or she loses a party primary. If states also moved to eliminate this undemocratic rule, incumbents could wage a principled campaign in defense of moderation in the primary, and if they lose, come back to run in the general election as an independent. Joe Lieberman did this in Connecticut after losing the Democratic primary in 2006, and he won as an independent—because Connecticut is one of the few states without a sore loser rule.