Massachusetts Institute of Technology Economics professor Jonathan Gruber testifies before the House Oversight and Government Reform Committee about his work on the Affordable Care Act in the Rayburn House Office building on Capitol Hill December 9, 2014 in Washington, DC. Gruber, who was a consultant paid by the authors of the Affordable Care Act and the Massachusetts universal health care program, called voters stupid and said that Obamacare would not have passed if lawmakers had really known what was inside the legislation during an academic conference earlier this year. Massachusetts Institute of Technology Economics professor Jonathan Gruber testifies before the House Oversight and Government Reform Committee about his work on the Affordable Care Act in the Rayburn House Office building on Capitol Hill on Dec. 9, 2014 in Washington, D.C. (credit: Chip Somodevilla/Getty Images)

MONTPELIER, Vt. (AP) — A Massachusetts Institute of Technology health economist who made national headlines last year for talking about “the stupidity of the American voter” was a target Monday in a report from the Vermont state auditor saying the economist may have padded his bills to the state.

Auditor of Accounts Douglas Hoffer said he referred his findings on Jonathan Gruber and his contract with the state to Attorney General William Sorrell. Hoffer said Gruber’s invoices billed Vermont $100 per hour for the work of a research assistant — 1,000 hours in 10 weeks.

“To do so, the RA would have worked exclusively on this project for more than 14 hours per day — every day,” the auditor said. “The evidence suggests that Dr. Gruber overstated the hours worked by the RA and that the Agency of Administration ignored the obvious signs that something was amiss.”

The attorney general said in an interview that Hoffer raised “serious questions.”

Gruber said in an email Monday he did not wish to comment.

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An adviser to the Obama administration on the federal Affordable Care Act, Gruber told groups in 2012 and 2013 that voter stupidity and a “lack of transparency” were important to passing the hard-fought legislation. He has apologized repeatedly for his comments, saying they were uninformed, “glib, thoughtless and sometimes downright insulting.”

Vermont Administration Secretary Justin Johnson said Monday the two state officials working with Gruber, Robin Lunge and Michael Costa, were in contact with him frequently enough — sometimes multiple times a day — to monitor his work.

Still, Johnson said he is urging staff to step up contract vigilance, and he agreed with Hoffer’s criticism that Gruber’s invoices need more detail. He said state officials had assumed Gruber had multiple assistants working with him, but later learned there was just one.

“We feel that the work was done, but clearly it would have been better if we had documented that and they had documented that,” Johnson said.

Hoffer said the round numbers in Gruber’s invoices were a red flag.

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“It is noteworthy that Dr. Gruber’s first invoice reported round numbers of hours worked (100 for Mr. Gruber and 500 for the research assistants),” Hoffer wrote. “This is possible, but unlikely. In addition, the second invoice reported exactly the same figures, which is implausible.”

Vermont contracted with Gruber in July to do economic modeling for Green Mountain Care, a universal, publicly-funded health care system that had been in development since the Legislature passed and Gov. Peter Shumlin signed a bill in 2011 to create the system. Shumlin ended up pulling the plug on Green Mountain Care in December, saying it would be too expensive.

Johnson said the state has paid $160,000 to date on what initially was a $450,000 contract, including $50,000 for a subcontractor.

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