While the Patient Protection and Affordable Care Act is garnering plenty of criticism as it enters its third open enrollment period, there is at least one provision of the landmark health law that many of the law's critics may soon be forced to embrace: the federally-funded expansion of Medicaid.

Montana became the 30th state to take part in the expansion on Monday, when the Obama administration approved the state's request for the additional federal funds, which will guarantee coverage for those living up to 133 percent of the federal poverty level.

Almost entirely financed by the federal government –– at least in the near future –– the expansion has extended coverage to millions of low-income Americans while avoiding many of the problems that have bedeviled the private insurance exchanges.