(Bloomberg) — Jonathan Gruber, the economist whose remarks on the Patient Protection and Affordable Care Act (PPACA) have drawn criticism from Republicans, apologized to lawmakers for being “glib, thoughtless and sometimes downright insulting.”

In testimony today at a U.S. House committee hearing, the Massachusetts Institute of Technology professor sought to explain his comments in a 2013 panel discussion. He said then that the PPACA was drafted “in a tortured way” to mask what was essentially a tax on the insured, relying on “the stupidity of the American voter” to ensure passage.

“In some cases I made uninformed and glib comments about the political process behind health-care reform,” Gruber said today. “I am not an expert on politics, and my tone implied that I was, which is wrong. In other cases I simply made insulting and mean comments that are totally uncalled for in any situation.”

Gruber said he wasn’t an “architect of Obamacare,” as Republicans have characterized him. He designed microsimulation models to help the Obama administration and congressional Democrats estimate the impact of their policies, he said.

“You made a series of troubling statements that were not only an insult to the American people but revealed a pattern of intentionally misleading the public about the impact and true nature of Obamacare, which in many ways you helped craft,” Rep. Darrell Issa, R-Calif., said to Gruber at the hearing. Issa also referred to Gruber’s statement about the American voter by asking Gruber himself, “Are you stupid?”

Enrollment error

Gruber sat next to Marilyn Tavenner, administrator of the Centers for Medicare and Medicaid Services (CMS), who was at the hearing to testify about an error the agency made in reporting the number of people enrolled in PPACA exchange plans. The agency mistakenly included about 393,000 in dental plans in its figure of 7.3 million enrollees in private coverage earlier this year, an error first reported last month by Bloomberg News.

“While this mistake was regrettable, it shouldn’t obscure the fact that the Affordable Care Act is working,” Tavenner said today.

“It had the same effect as Dr. Gruber’s statements,” Rep. Elijah Cummings, R-Md. “It gives ACA opponents a PR gift that they can use on cable shows and elsewhere to attack the ACA. It’s an unforced political error.”

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