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The company’s seemingly bright prospects also got the attention of the White House.

“There’s A123, a clean-energy manufacturer in Michigan that just hired its 1,000th worker as demand has soared for its vehicle components,” the president said in July 2011.

Earlier this month, Mr. Grassley and Mr. Thune pressed Energy Department officials to explain whether the department performed “due diligence” before awarding the company so much money.

“The bankruptcy raises the prospect that taxpayers will get little or no return on their investment in A123 and will lose millions of dollars,” they wrote, adding that the “administration needs to answer for this. The taxpayers shouldn’t have to subsidize poor investments in failed energy companies.”

Mr. Thune called the A123 stimulus package “another example of President Obama gambling with taxpayer dollars and picking winners and losers in the green energy world.”

“There were clear warning signs that A123 was having financial problems even as the administration continued pouring millions of taxpayer dollars into this failing company,” he said.