Among the most hotly debated of the issues Hillary Clinton and Bernie Sanders have taken on in the Democratic primary contest is how best to get to universal health insurance coverage. The former secretary of state favors incremental steps, and the senator calls for a single-payer system. That debate, and their focus on universal coverage as their goal, appears to have had a modest and perhaps surprising effect on attitudes toward the Affordable Care Act. The health-care law is an issue about which public attitudes seldom shift, yet the share of Democrats who want to expand the Affordable Care Act rose over the past year.

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