Tom Cotton, our junior U.S. senator, gamely faced a couple of thousand constituents in Springdale last week in a bit of political theater that was irresistible to the national news networks.

CNN, in a laughably ignorant error, called northwest Arkansas “a pocket of relatively liberal voters in the red state.” But Sen. Cotton knows better. He knows that liberals were over-represented in that high school auditorium, so chants for President Trump’s tax returns and questions about a border wall bounced off the senator’s white shirt.

But there is an issue that can’t be swatted away: Obamacare. Arkansas smartly accepted federal taxpayers’ money to insure its working poor. Because we have so many of those folks — many employed by Arkansas Business readers — one in 10 Arkansans is insured through the program now known as Arkansas Works.

The repeal of the Affordable Care Act would directly impact them. And every Arkansan with a pre-existing condition. And young adults who can now stay on their parents’ plans until age 26. And premature infants who, before the ACA, would have reached their lifetime benefit caps before ever sleeping in their own cribs. Arkansas has benefited from Obamacare more than any other state except perhaps Kentucky.

President Trump and Republicans in general have promised to keep all the parts of the ACA that Americans love while getting rid of the part that they find so offensive: the individual mandate that everyone must buy insurance if they can afford it. This is magical thinking.

Insurance is shared risk. You can’t buy auto insurance after the wreck or homeowners’ insurance when the house is on fire. If consumers aren’t required to pay into the pool until they get sick but insurers are required to accept them, the time between signing the ACA replacement and the collapse of the insurance market will be measured in nanoseconds.

And if Americans with pre-existing conditions are no longer insurable, even red-state Republicans like Cotton could find themselves politically vulnerable.