Editor’s note: In addition to Christine Vestal (photo and linked bio above), this post was coauthored by Michael Ollove, a senior reporter at Stateline.

President Obama’s re-election puts the Affordable Care Act on firm ground for the first time since it was enacted. Now it is up to states to decide whether and how they want to participate.

At issue are two major decisions: whether states are willing and able to run their own health insurance exchanges, and whether they will consent to expanding their Medicaid programs to everyone with an income up to 133 percent of the federal poverty line, as envisioned in the law.

Most Democratic-led states are expected to fully participate in both, although some may seek flexibility. But among the 30 states that will be run by GOP governors starting next year, it is unclear how many will opt in. Many predict that the federal government’s offer of covering the full cost of the Medicaid expansion for the first three years, and 90 percent after that, will be too rich for states to refuse.

The first order of business is committing to running an exchange, entering a partnership with the federal government or opting out altogether. That decision is due next Friday, November 16. For some Republican-led states that have put off the uncomfortable decision to implement a law they oppose, a state-run exchange may no longer be an option.

So far, no deadline has been set for a decision on expanding Medicaid, but states can be expected to address the issue sooner rather than later. When state legislatures open next year, Medicaid expansion will be at the top of most agendas. Meanwhile, states will be carefully watching to see how much the federal government decides to reduce its share of Medicaid funding when a final deficit reduction law is enacted in January.

Both decisions will profoundly affect consumers and the health care industry, as well as state budgets, for years to come. The Obama administration can be expected to work closely with states to ensure that as many as possible participate. Unless most engage, the Affordable Care Act’s aim of covering 30 million uninsured people may not materialize.