Democrats have been making the case that Amy Coney Barrett becoming a Supreme Court Justice would put ObamaCare in jeopardy.
The logic is that since Judge Amy Coney Barrett argued against the Affordable Care Act (ObamaCare) when she was a law professor and that she would thus likely rule in favor of the upcoming Supreme Court case that declares the ACA illegal. If the case wins in the Supreme Court that means all of the Affordable Care Act would effectively be repealed.
Thus, the reasoning is that confirming Judge Barrett will have a direct impact on the fate of the ACA, and thus confirming Barrett is akin to voting for ACA repeal.
For more, see CNN’s “What Amy Coney Barrett could mean for Obamacare.”