Sunday night, the campaigns for Republican presidential candidates Ted Cruz and John Kasich announced that they were collaborating in a bid to block Donald Trump from winning a majority of pledged delegates. Kasich would neither campaign nor spend resources in his neighboring state of Indiana, while Cruz would similarly stand down in New Mexico and Oregon. Nate Cohn of the New York Times' Upshot suggested the deal "has the potential to stop Trump."
Count me as a skeptic in our plurality, "top of the heap" voting system. Already the deal is fraying, as it's a bad message to send to supporters that one isn't going to campaign for their votes. Just as Marco Rubio's plan in March to stand down in Ohio likely hurt him in Florida, the easy impression for voters is what Donald Trump said: the deal "shows weakness."
Far more sensible would be to simply free voters to indicate their backup choices with ranked choice voting, and conduct an instant runoff to determine the head-to-head winner. Indiana would be a dead heat with ranked choice voting, according to polls that compare Cruz and Trump head-to-head -- but I suspect this proposed deal won't achieve that objective.