LAS VEGAS (AP) — The Nevada caucus, the third contest in the Democratic presidential race, is Saturday. One of the key questions is how well Sen. Bernie Sanders does. If he wins, he solidifies front-runner status heading into South Carolina next week and, more important, into critical Super Tuesday primaries on March 3. But if something goes wrong, or he only barely pulls out a win, it will intensify questions about whether the self-declared democratic socialist can extend his support beyond his fervent base. Other key questions are the role of labor, voter turnout, whether the field will this out, and the role of minority voters.