A Senate hearing on “shoppable” healthcare devolved into a fiery debate over the future of the Affordable Care Act’s enhanced subsidies, the key dispute driving the government shutdown, as Democrats claim millions could lose coverage if the credits lapse.

The hearing, led by chairman Rick Scott (R-FL) and ranking member Kirsten Gillibrand (D-NY), was billed as a discussion on how transparency and consumer choice could lower costs for older Americans. But it quickly became a proxy battle over the shutdown and whether to extend the ACA’s premium tax credits, which expire at the end of the year.