The ACA, known colloquially as Obamacare, is a federal statute signed into law by Obama on 23 March 2010. Alongside the 2010 Health Care and Education Reconciliation Act amendment, the ACA represents the most significant reform and expansion to the American healthcare system since the 1965 passage of Medicare and Medicaid. The ACA cut the uninsured share of the American population roughly by half by 2016. It overhauled the individual insurance market, while largely retaining the existing structure of the employer market, Medicare, and Medicare. Insurers were made to accept all applicants, even those with preexisting conditions. Further, the ACA ensured that insurers cover a list of essential health benefits, such as preventative services, prescription drugs, and maternity care. Obama received both praise and criticism for the ACA. While generally praised by Democrats, those who favor a single-payer system argue that the ACA does not go far enough. By contrast, Republicans overwhelmingly oppose the ACA. Since its enactment, Republicans have voted to repeal all or parts of the ACA more than 60 times. None of these attempts have been successful.