In March 2010, days before former President Obama signed his healthcare legislation into law, the Congressional Budget Office estimated that by 2017, 23 million people would be obtaining insurance through the program’s exchanges. In a new report issued Tuesday, the CBO said that the actual number for 2017 would be 10 million, or less than half of that.

The new projections by the CBO come at the start of a heated debate over repealing and replacing Obamacare. The relatively low enrollment numbers (and specifically the difficulty that insurers have had signing up young and healthy individuals to offset the cost of covering older and sicker enrollees) have dogged Obamacare. Money-losing insurers have raised premiums, narrowed choices of doctors and hospitals, and in some cases, exited markets altogether.