It is called instant runoff voting, or IRV for short, and proponents say it is a simple, doable way to make elections fairer and bring alienated voters back into the electoral fold.
According to the Center for Voting and Democracy, IRV works like this:
"Each voter has one vote, and ranks candidates in order of choice (1, 2, 3, etc.). The counting of ballots simulates a series of run-off elections. All first choices are counted, and if no candidate wins a majority of first choices, then the last place candidate (candidate with the least first-choices) is eliminated. Ballots of voters who ranked the eliminated candidate first then are redistributed to their next-choice candidates, as indicated on each voter's ballot. Last place candidates are successively eliminated and ballots are redistributed to next choices until one candidate remains or a candidate gains over 50 percent of votes." One appealing aspect of instant runoffs, say proponents, is that they allow voters to support a potentially marginal third party without fear that they will "waste" the vote or split a coalition so that the candidate the like least wins.
It is an idea that has been gaining support in some areas, New Mexico being a particularly good example, where Green Party candidates have been drawing enough support away from Democrats to swing elections in favor of Republicans, something members of both progressive camps don't want to happen. "Voters have every incentive to vote for their favorite candidate rather than the 'lesser of two evils' because their ballot can still count toward a winner if their first choice loses. There also is every reason for a voter to rank as many candidates as they want, since a voter's lower choice will never help defeat one of their higher choices."