The Map

Iowa has a progressive tradition, and Mr. Sanders will no doubt find support in the more populist and dovish quarters of the state. To emerge as a threat, though, he would need to win over more of the state’s moderate Democrats. If he can do that, Mr. Sanders could find similar support in New Hampshire, particularly along the western spine of the state, home to many of the state’s most liberal voters. But if Mr. Sanders fails to win much more than 10 percent of support from the caucusgoers and voters in those first two states, whose electorates are overwhelmingly white, he will have a hard time remaining viable when the race turns to South Carolina, where blacks can make up more than half of the primary electorate.