(Bloomberg View) — Congress's failed effort to undo Obamacare this year revealed an important political shift in the U.S.: Americans are no longer content to let people go without health insurance. As the Affordable Care Act has taken root, most have come to believe the federal government has a responsibility to make sure everyone is covered.

Republicans should take note: Another stab at destroying Obamacare is not what voters want. Instead, both parties should dedicate themselves to building on it — and, to that end, work is needed by the end of this month, when insurers are due to sign contracts to sell policies on the state exchanges next year.

To be sure, merely shoring up Obamacare won't bring universal coverage. The law has cut the number of uninsured by half, but 26 million people remain without coverage, and that number is expected to rise. To eliminate this gap, big new initiatives are needed: automatic enrollment of the uninsured into subsidized, no-frills plans, for example, or state programs that let people buy Medicaid policies.