The Democratic primary is the House that Bernie built

HOLLIS, N.H. — Bernie Sanders vaulted to the top of the Democratic field by dominating the debate and controlling the agenda, party stalwarts believe, even as they harbor doubts about the Vermont senator’s viability.

Joe Biden, the only Democrat to consistently out-poll Sanders, launched his campaign Thursday. The former vice president will no doubt affect the trajectory of the race. But it is a 77-year-old socialist who has been the axis around which each of the other nearly two-dozen candidates revolve.