James Capretta explains at National Review Online why it would be a mistake for Republicans to pursue a plan to repeal the Affordable Care Act without replacing it.

Regardless of Trump’s inclinations, however, it would be a terrible idea — for substantive and political reasons — for Republicans in Congress to pursue repeal without replace in 2017.

One reason it would be a bad idea is that the legislation Congress sent to the president earlier this year wasn’t really a full repeal bill anyway. It eliminated the ACA’s individual and employer mandates by reducing the penalties for noncompliance to zero, and it repealed numerous, discrete tax and spending increases in the ACA. It also terminated the ACA’s massive Medicaid expansion and subsidies for insurance purchased on the exchanges — but only after 2017.

That was telling. Many Republicans in Congress wanted to say they were repealing the ACA, but they didn’t want to be held responsible for pushing out of coverage people who had become insured because of the new law. The two-year delay in repealing the ACA’s Medicaid expansion and insurance subsidies allowed GOP leaders to claim they weren’t increasing the ranks of the uninsured, given that they planned to pass a replacement plan, with an alternative coverage expansion, before the end of 2017.

The GOP passed its modified repeal bill under the rules of budget reconciliation. The budget reconciliation process provides for expedited consideration of legislation in Congress. This is particularly important in the Senate, where legislation often requires the support of 60 senators to overcome a filibuster. Using the reconciliation process allowed the GOP majority to pass its modified ACA repeal bill without any votes from Democratic senators.

But the use of reconciliation also constrained what lawmakers could put into the bill. In general, budget reconciliation bills are not supposed to include provisions that are mainly regulatory in nature. The GOP’s repeal bill, therefore, did not eliminate the ACA’s extensive regulations of the insurance industry, such as the prohibition against the use of health status in setting premiums or coverage.

The repeal bill’s effective elimination of the individual mandate, coupled with retention of the ACA’s insurance regulations, would lead to a full collapse of the individual-insurance market.