On the eve of the Wisconsin primaries, top Republicans are becoming increasingly vocal about their long-held belief that Speaker Paul Ryan will wind up as the nominee, perhaps on the fourth ballot at a chaotic Cleveland convention. One of the nation’s best-wired Republicans, with an enviable prediction record for this cycle, sees a 60 percent chance of a convention deadlock and a 90 percent chance that delegates turn to Ryan — ergo, a 54 percent chance that Ryan, who’ll start the third week of July as chairman of the Republican National Convention, will end it as the nominee.