Romney specifically mentioned the health law's Independent Payment Advisory Board six times that night, alleging the panel will make decisions about patients' medical care.
On Tuesday, however, most references to the Affordable Care Act and to Medicare were general and brief.
"You know, there are some things where Gov. Romney is different from George Bush," Obama said at one point. "George Bush didn’t propose turning Medicare into a voucher."
The comment referred to Romney's support for partially privatizing Medicare, a major point of criticism from Obama. The GOP nominee argues the plan is needed to keep Medicare solvent into the future.
Romney returned Obama's fire on healthcare by blasting the president's reform law as an "extraordinary deterrent to enterprises of all kinds hiring people." Obama disputes this point and says the law was necessary to expand healthcare coverage and to rein in costs.
Romney also blasted Obama for not "making a proposal" to reform Medicare. The Obama campaign has noted that analysts have said the healthcare law will extend Medicare's life span by eight years.
The candidates did spar on Obama's birth control coverage mandate. Read more about that exchange here.