After years of promising to “repeal and replace Obamacare,” the Republican Party is finally in the position to follow through this year, and party leaders are beginning to understand the challenges that come with the promises they’ve made regarding the Affordable Care Act.

One of the big issues the GOP is facing: Many of the communities with the biggest increases in health insurance coverage since 2008 were Republican-leaning places that voted for President-elect Donald Trump.

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In December, a Wall Street Journal story outlined how many counties that voted heavily for Trump also saw increases in health insurance coverage greater than the overall national increase. Those counties, categorized by the American Communities Project, were largely rural and white, with many holding large evangelical populations, and scattered throughout the key states that won Trump the presidency.

Below is a look at some counties in swing states that went heavily for Trump and that also saw noteworthy drops in their uninsured rates during Barack Obama’s time in the White House.

Data from Gallup showed that between 2008 and 2016, there was a 3.9% decrease in the number of uninsured Americans. All these counties saw larger drops than that between 2008 and 2014, according to numbers for the Census Small Area Health Insurance Estimates. There are many more. (The most recent set of data is from 2014.)

To be clear, an increase in coverage does not necessarily equal support for the ACA. Just because people follow a government mandate doesn’t mean they support the mandate. But the data suggest that if the ACA is “repealed” and not “replaced,” communities that voted for Trump would see some of the biggest drops in coverage.

That’s likely one of the big reasons why the “replace” part of the GOP equation has gotten much more of the attention recently. Just this past week, Trump adviser Kellyanne Conway stressed that, “We don't want anyone who currently has insurance to not have insurance.”

Opposing the ACA is one thing. But taking away health coverage is not the kind of approach that keeps current voters happy or wins new ones.

That’s the complicated terrain the GOP now finds itself facing as it tackles Obamacare. And as the idea of “repeal and replace” gets closer to reality, you can expect those political concerns to exert an increasingly strong pull on the coming Trump administration and the new Washington.