Across the country, hospital operators like Tenet Healthcare THC +1.65% and HCA Holdings HCA +0.38% as well as health insurers with substantial Medicaid contracts like Aetna AET -1.28%, Anthem ANTM +0.22%, Centene CNC -1.65% and UnitedHealth Group UNH -0.94% have been lobbying holdout states to expand.

From 2014 through this year, the expansion population is funded 100% with federal dollars.

Beginning next year, states gradually have to pick up some costs, but the federal government still picks up 90% or more of Medicaid expansion through 2020. It’s a better deal for states then before the ACA when Medicaid programs were funded via a 50-50 split between state and federal tax dollars.

There are 31 states plus the District of Columbia that have opted to expand Medicaid. Louisiana’s new Democratic governor John Bel Edwards, who was elected to replace the outgoing Republican and former GOP presidential candidate Bobby Jindal,signed an executive order in January to make the state the 31st to take advantage of a generous federal funding stream to expand Medicaid benefits.

Supporters of Medicaid expansion in Idaho wanted Otter to consider an executive order, but he wouldn’t do so, keeping what he called a promise he made to Idaho residents after the Supreme Court ruled in 2012 that states had the option to expand the program under the ACA. President Obama signed the ACA into law in 2010, with broader coverage kicking in two years later.

Now, any expansion of health benefits in Idaho to the 78,000 uninsured will be left to a “working group” of lawmakers and other state policymakers.

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I write about health care and policies from the president’s hometown