Fifty-seven percent believe the federal government is responsible for making sure all Americans have health care coverage, while 41% think it is not. …

Among all Americans, 42% support a single-payer plan like the one espoused by [Sen. Bernie] Sanders, while 31% express opposition. Another quarter say they are neither in favor nor opposed. Support breaks down along partisan and ideological lines, with liberal Democrats about four times as likely as conservative Republicans to back single-payer.

Christine Knapp, a Republican from Fresno, California, is concerned that Sanders’ approach might affect her current Medicare coverage. …

The partisan gap narrows significantly, however, for the option of Americans buying into a government program.

Overall, 53% support the buy-in option, with 17% opposed and 29% on the fence.

Similar shares of Democrats back the two plans. But Republicans are nearly twice as likely to support a public option plan as a single-payer plan, 44% to 22%.