All candidates agreed that private insurance system is inadequate in covering everyone and/or inadequate in covering the needs of those who are insured.
All candidates agreed that at a minimum, a public option is required to fill the gap and compete with private insurance. The disagreement was whether to let that option evolve and be tested in the market as the original ACA model contemplated or do the Full Monty per Warren and Sanders contemplate.
Almost all nominees want Americans to have options and choices between public vs private vs a hybrid plan.