Because of the healthcare law, the White House says nearly 3 million young people under the age of 26 have been able to stay on their parents’ insurance plans and don’t have to shop for coverage on HealthCare.gov.

That’s about double the number of young people between the ages of 18 and 25 who are currently covered through the exchanges.

“I think that is an argument that has some validity,” John McDonough, a senior adviser to the Senate committee that wrote ObamaCare, said in an interview.

“If we didn’t allow these kids to go on their parents’ plans, many of these kids would have gone to the exchange and would have created a more stable marketplace under the exchange,” said McDonough, who now teaches at the Harvard T.H. Chan School of Public Health.