Ensuring the Future of the Affordable Care Act on the Health Insurance Marketplaces.

CONTEXT: A decade after passage, a majority of Americans now support the Affordable Care Act (ACA), and Republican efforts to repeal it outright have failed. This article investigates whether the policy itself, through its beneficiaries, changed public opinion and sowed the seeds of its defense.

METHODS: This study used an individual-level panel design to estimate the causal effect of implementation on opinion and electoral outcomes for ACA beneficiaries during the first year of open enrollment.

FINDINGS: Individuals who enrolled in plans on the health insurance marketplaces had significantly more positive opinions of the ACA after implementation. Previously uninsured Medicaid enrollees also reported improved opinions, though results were not statistically significant. In contrast, uninsured individuals residing in states that did not expand Medicaid became significantly less supportive of the law. Changes in opinion persisted up to the 2014 midterm elections, and there is evidence that individuals with marketplace insurance became more supportive of Democratic candidates, although not more likely to vote for them.

CONCLUSIONS: Public support for the ACA was enhanced when its beneficiaries became more positive toward it during implementation. Recent changes to key ACA provisions have the potential to undermine the law's effectiveness, potentially leading to political action as benefits slowly begin to disappear.