Half of those who still lack health insurance are eligible toreceive subsidized health care through the Patient Protection andAffordable Care Act.

A new study by the Kaiser Family Foundation finds that of the32.3 million non-elderly Americans without health coverage, 49percent could either sign up for Medicaid or receive financialassistance to purchase insurance on the PPACA insuranceexchanges.

Ten percent of the total number of uninsured are children whoare eligible for CHIP, the youth Medicaid program. Seventeenpercent are Medicaid-eligible adults and 22 percent are people whocould receive subsidized care through the PPACAmarketplace.

But that means there remain 51 percent — or roughly 16 millionpeople — who lack insurance but are not able to receive anygovernment support in order to get it.

Fifteen percent of the uninsured are ineligible because of theirimmigration status. In recent weekssome Democrats have called for opening the PPACAexchanges up to undocumented immigrants, a proposal that is anon-starter in a GOP-controlled Congress.

Another 15 percent of the uninsured are ineligible for subsidiesbecause they are able to get insurance through theiremployer.

Only 12 percent of the uninsured are ineligible simply becausethey have too much money to qualify for subsidies.

Finally — and perhaps most important politically — 10 percent ofthe uninsured are ineligible for both Medicaid and marketplacesubsidies because they fall into the "coverage gap" created bystates that refused to participate in the federally-funded Medicaid expansion that was a key component ofPPACA. That means they make too much money to qualify for theirstate's Medicaid program but too little to qualify for premiummarketplace tax credits.

In the states that didn't expand Medicaid, the "coverage gap"people account for 19 percent of the uninsured. In fact, only 3percent of the uninsured in such states areMedicaid-eligible.

In contrast, in states that did expand Medicaid, 30 percent ofthe uninsured are Medicaid-eligible.

As PPACA open enrollment approaches its two year anniversary,getting those who remain without insurance onto the health carerolls is going to be tough.

Kaiser concludes: "(T)here are still substantial opportunitiesto increase coverage by reaching those who are eligible for helpunder the ACA, but the breakdown of who the remaining uninsured aresuggests that many may be difficult to reach and will still remainuninsured."