There are 28 million uninsured under Obamacare. Here’s who they are.

White House press secretary Sean Spicer posted a tweet Wednesday bemoaning the 28 million Americans who remain uninsured under the Affordable Care Act.

Setting aside the fact that the Trump administration has supported legislation that would cause millions more Americans to lose coverage — something I wrote about in more detail here — it is worth taking a moment to look at who these 28 million people are, and why they lack coverage. Among them are unauthorized immigrants, low-income people in states that didn’t expand Medicaid, people who decided insurance was too expensive, and some who just decided to take the risk and live without it.

Nonprofits, which have done a lot of great research on this question, find that about half of the uninsured population doesn’t qualify for help from the Affordable Care Act. The other half, for various reasons, have not enrolled in coverage:

The Affordable Care Act bars undocumented workers from using the health care law’s marketplaces. This isn’t just about using the tax credits; undocumented workers are not allowed to use their own money to buy coverage through Healthcare.gov, either.

The Kaiser Family Foundation estimates there are 5.4 million people living in the United States who are ineligible to use the Affordable Care Act marketplaces due to their immigration status. These people could, hypothetically, buy coverage outside Healthcare.gov directly from health insurance brokers. But they might find that without tax credits, the premiums are prohibitively expensive.

An additional 3 million low-income Americans are estimated to live in the 19 states that have not expanded Medicaid. In these states, people who earn less than the poverty line (below about $12,000) do not qualify for tax credits to purchase private coverage.

The Affordable Care Act envisioned that these people would enroll in the Medicaid expansion, but a Supreme Court decision in 2012 made that part of the health law optional — leaving millions in a coverage gap.

The Kaiser Family Foundation estimates that 43 percent of the uninsured do qualify for help purchasing insurance on the marketplaces but still aren’t enrolled. Many say that even after they qualified for financial help, they still didn’t find the coverage they could purchase on Healthcare.gov affordable. This is one survey the Commonwealth Fund, for example, did of Americans who visited the marketplace but ultimately decided not to purchase a plan.

The vast majority (86 percent) who had gone to look for a plan said they didn’t feel the options were affordable. Most (54 percent) earned too much to qualify for the Affordable Care Act’s tax credits, and felt that the premiums were too high to afford on their own.

But some people who qualify for tax credits didn’t think the coverage was worth the money either. These people tended to be younger and healthier Americans, who’d rather chance life without health insurance.

“When I looked into it, it looked like the penalty would be cheaper than paying for it every single month,” says Damen Archer, a 38-year-old bartender whom I interviewed a few months ago at the Par-T-Pub in Maryville, Tennessee. Archer qualified for significant subsidies and had looked into signing up, but did the math and decided he’d rather just pay the individual mandate penalty for not having insurance. “The penalty is what, $680, something like that? I think the best price I found was $120 a month. So you’re looking at $1,200 versus $600.”

The uninsured were also much less likely to be aware that the coverage expansion existed. The same Commonwealth Fund survey found that 38 percent were not aware the new health care marketplace existed in their state. This is a lower number than the fund found in an earlier iteration of the survey, suggesting awareness is rising but a sizable chunk of the uninsured population still doesn’t know that these new programs exist.

“The vast majority [of the remaining uninsured] have low incomes, are young, are Latino, and/or are working in a small firm,” the Commonwealth Fund brief concludes. “They are also less aware of the marketplaces than most Americans.”

The Republican plans to repeal and replace the Affordable Care Act would make these problems worse, causing the ranks of the uninsured to rise by at least 22 million.

Low-income Americans would see an especially sharp rise in uninsured rates, as the Republican plans would put health insurance even further out of financial reach.

As the Congressional Budget Office concluded starkly in its last analysis, despite being eligible for premium tax credits, “few low-income people would purchase any plan” under the Senate Republicans’ health care plan.