The share of working-age adults without health insurance has increased for the second year in a row, according to a new report by the Commonwealth Fund. In the group’s latest annual tracking poll, 15.5 percent of Americans between 19 and 64 said they lacked coverage, up from 14 percent last year and 12.7 percent during President Obama’s final lap in office, when the uninsured numbers hit a historic low.

But there’s an odd political caveat: At the moment, the uninsured rate only seems to be rising for Republicans.

The Commonwealth Fund isn’t the only organization to find a drop in health coverage. Gallup’s last tracking poll found that the uninsured rate had risen 1.7 percentage points since the end of 2016. To some extent, that’s not surprising. The White House’s attempts to undermine Obamacare have driven up the sticker price of health plans sold on the individual market, which has surely led some people to drop their coverage. What’s somewhat more puzzling is that both Gallup and Commonwealth find that the biggest drops in coverage have occurred among lower-income households, who typically qualify for subsidies under the current health law. Commonwealth found that the entire decrease in coverage last year occurred among households making less than 250 percent of the poverty line.

That’s a bit odd because, for the most part, lower-income families should not have seen the cost of their insurance go up much, if at all, since the Affordable Care Act caps their premiums at a percentage of their income. In fact, the cost of insurance ended up dropping for many subsidized insurance customers this year, because of how states reacted after Donald Trump cut off certain payments to insurers. And while it’s true that Republicans repealed the individual mandate as part of their tax law, that change doesn’t take effect until 2019. At the moment, Americans are still required to buy coverage as before.

One likely explanation is that some impoverished Americans are dropping their insurance because they fall into Obamacare’s dreaded “coverage gap”— meaning that they earn too little to qualify for the law’s premium subsidies, but too much to qualify for Medicaid, because their state chose not to expand the program as the Affordable Care Act’s architects originally envisioned. If these poor households want health insurance, they have to pay the full cost of a private plan. And with unsubsidized premiums rising rapidly, many are probably being priced out of the market. The fact that the uninsured rate is increasing much faster in states that didn’t expand Medicaid suggests this population is a big part of the problem.

Still, that doesn’t seem to be the entire story. One of the most puzzling findings in the Commonwealth Fund report is that, last year, the uninsured rate only increased among Republicans. That’s surprising, since even in deep red states that didn’t expand Medicaid, many low-income minority communities where people are at risk of falling into Obamacare’s coverage gap tend to vote Democrat. And yet, Commonwealth found no statistically significant change in the uninsured rate among Democrats or independents; among Republicans it rose 4 percentage points.

This is just one year’s result in a single tracking poll, so I don’t want to over-interpret it. But the finding is both odd and a bit hard to explain. Sara Collins, vice president of Health Care Access and Coverage program at the Commonwealth Fund, suggested that a lot of Americans may have just been confused about their health care options, after Republicans tried to repeal and replace Obamacare, especially because the Trump administration slashed the program’s advertising and outreach budget. And in fact, polls have shown that there’s an enormous amount of confusion among voters about whether Trump actually repealed the ACA, either fully or partly, with Republicans much more likely to believe he undid the law.

In other words, it’s possible that the country’s uninsured rate is rising in part because Republicans Jedi-mind-tricked their own voters into believing that they killed off Obamacare, despite mostly failing to do so. It’d almost be impressive, if it wasn’t so heinous.