Members of the House Committee on Oversight and Government Reform grilled Jonathan Gruber, an MIT economist and former adviser on the Affordable Care Act, for controversial comments he made about the law. (Julie Percha and Rebecca Schatz/The Washington Post)

This post was updated at 12:30 p.m.

Economist Jonathan Gruber apologized Tuesday for his “thoughtless” and “glib” past comments about the political process behind the Affordable Care Act, which sparked controversy when the remarks were newly unearthed last month and put him at the center of the public debate over the law.

“In some cases I made uninformed and glib comments about the political process behind health care reform. I am not an expert on politics and my tone implied that I was, which is wrong,” Gruber told the House Oversight and Government Reform Committee. “It is never appropriate to try to make oneself seem more important or smarter by demeaning others. I know better. I knew better. I am embarrassed and I am sorry.”

Gruber sparked a firestorm last month when several videos surfaced in which he called American voters “stupid,” suggesting that a “lack of transparency” in the Affordable Care Act contributed to passage of the law. Critics of the ACA, who called Gruber the "architect" of the health care law, seized on the comments to call into question the law’s validity, while Obamacare supporters distanced themselves from Gruber and widely disparaged his remarks.

In this CSPAN clip from March 2010, economist Jonathan Gruber talks about cost control of health care and why the public focused on that aspect of the Affordable Care Act. (CSPAN)

“I'm a professor of economics at MIT. I'm not a politician nor a political advisor," Gruber said, stressing that his role with the administration was purely technical. "I did not draft Governor Romney’s health care plan, and I was not the ‘architect’ of President Obama’s health care plan.”

The hearing featured several terse exchanges, which highlighted the lighting rod Gruber has become and the sharp partisan divisions surrounding the ACA.

"Are you stupid?" committee chairman Rep. Darrell Issa (R-Calif.) asked at one point.

"I don't think so, no," said Gruber.

“So you're a smart man who said...some really stupid things,” said Issa.

“The comments I made were really inexcusable,” responded Gruber.

Several Republican members inquired about the exact amount Gruber was paid for his work as a consultant, which Gruber repeatedly declined to answer. At several points Gruber avoided the question by maintaining that his attorney had counseled him that financial documents already submitted to the committee had met the disclosure requirements.

"So you're not going to answer the question? You come to the committee, we ask a question, and you’re supposed to answer the question," said Rep. Jim Jordan (R-Ohio). “We wanna know how much you got from the tax payers. Then [you] made fun of them after you got it from them.”

Gruber also faced a scolding by ranking committee member Rep. Elijah Cummings (D-Md.), who chided the economist for giving the law’s critics ammunition to disparage it and the administration.

"But worst of all, Dr. Gruber’s statements gave Republicans a public relations gift in their relentless political campaign to tear down the ACA and eliminate health care for millions of Americans,” Cummings said. “Man, you did a great job. You wrapped it up with a bow.”

The hearing is currently in progress. Centers for Medicare and Medicaid Services Administrator Marilyn Tavenner also testified on ACA enrollment.