One reason Republicans health plan failed? Millions of supporters could have lost coverage.

In a bizarre turn of events, House Republicans pulled their signature piece of legislation to repeal and replace the Affordable Care Act without even voting on it.

One possible reason is it could have been political suicide for them.

Obamacare created exchanges where individuals could shop for health insurance. These were supposed to be competitive marketplaces, but instead, many counties across the country have struggled to attract more than one insurer. These counties — which tend to be more rural and isolated — overwhelmingly voted for Donald Trump.

Paul Ryan’s health reform plan wouldn’t have fixed this problem. Instead, it would have had the opposite effect, largely making the problem worse and leaving millions of Americans without a place to buy health coverage.

This wasn’t entirely lost on Trump.

In an interview with Fox News host Tucker Carlson, Trump told Carlson he “knew” that counties that voted for him would do worse under the Republican replacement bill.

Of the nearly 1,000 counties with only one Healthcare.gov insurer, almost all of them (87 percent) voted for Trump in the 2016 election. And the 16 counties in dark red in the map above are places in Tennessee that will have zero insurers in 2018 because Humana has said it will exit the marketplace in 2018.

But it’s not just counties that voted for Trump that are suffering on the ACA marketplaces. There were 140 counties that voted for Clinton in 2016 (largely concentrated in the Deep South) that are now left with just one insurer.

As you can see in the map below, areas of Mississippi are particularly hard hit due to Humana pulling out of the marketplace exchange.

But compare them to the counties with one insurer that voted for Trump, and it’s easy to see that Trump supporters are disproportionately impacted. Trump supporters have a lot to lose if competition continues to decline in the marketplace.

Six states — Alabama, Alaska, Mississippi, Oklahoma, South Carolina, and Wyoming — will have only one insurer on the 2018 Healthcare.gov marketplace.

Mississippi is the latest state to join the growing ranks of states limited to one insurer option. In the 2017 Healthcare.gov marketplace, 40 percent of Mississippi’s counties had two insurer options, but with Humana’s exit, Ambetter from Magnolia Health is the only remaining insurer in the state. For the other five states that currently have only one insurer option on the 2017 Healthcare.gov marketplace, that probably won’t change in 2018.

What’s more, in states like Arizona, Missouri, and North Carolina, the number of insurer options is dwindling dramatically. In Arizona, only one county — Pima County — has two insurer options. And if Cigna were to pull out from the marketplace, both Missouri and North Carolina would be left with only one insurer in the state.

But as Vox’s Matt Yglesias points out, Obamacare isn’t “exploding.” And if President Trump is serious about health care reform in this country, he’ll work with Congress to improve the ACA instead of trying to dismantle it.