In a wide-ranging hearing Thursday that stretched from mid-morning well into the afternoon, U.S. Energy Secretary Steven Chu stoically defended his department's loan guarantee program, fielding a flurry of questions from suspicious lawmakers about the bankrupt solar power company Solyndra.

Many Republicans on the House Energy and Commerce panel were careful to explain that they consider Chu a "man of integrity," and aren't accusing him of any personal wrongdoing. But many also made sure to convey their anger over $535 million in lost taxpayer money, and to convey their theory that the Obama administration let politics trump economics.

"A central focus of the investigation is to understand why [the Department of Energy] did what it did and how we find ourselves with this taxpayer-funded debacle," said Rep. Fred Upton, R-Mich., early in the hearing. "The number of red flags about Solyndra that were raised along the way — many from within DOE — and either ignored or minimized by senior officials is astonishing."

A few minutes earlier, Rep. Cliff Stearns, R-Fla., had opened the hearing by alleging it's "readily apparent that senior officials in the Obama administration put politics before stewardship of the taxpayers' dollars." The purpose of the hearing, Stearns added, is to "determine why the department and the administration tied themselves so closely to Solyndra, and why they are so desperate to prop up this company."

In his opening testimony, Chu accepted blame for the Solyndra loan guarantee but insisted it was approved with good intentions. "As the Secretary of Energy, the final decisions on Solyndra were mine, and I made them with the best interest of the taxpayer in mind," Chu said. "I want to be clear: Over the course of Solyndra's loan guarantee, I did not make any decision based on political considerations."

Some Democrats on the panel defended Chu, including Rep. Henry Waxman of California, who suggested Republicans were the ones playing politics. "It is time for the Republicans to stop dancing on Solyndra's grave and get serious about energy policy," Waxman said. Rep. Ed Markey, D-Mass., later accused the GOP of piling on Solyndra because the fossil-fuel industry sees renewable energy as a threat. "Republicans attacked solar energy because they say it's too expensive," Markey said. "But Solyndra failed because the price of solar energy has become too cheap."

Several Republicans focused on a last-ditch restructuring of the loan, which Chu said was done to to avert certain bankruptcy in hopes of giving the company a "fighting chance." While taxpayer money was given priority for repayment in the original loan, the restructured version put private investors first — a "difficult decision," Chu said, but one he deemed necessary to muster enough money to keep Solyndra afloat.

Republican Phil Gingrey of Georgia, however, saw it differently. Drawing a comparison with last Sunday's NFL game between the Atlanta Falcons and the New Orleans Saints — a game Atlanta lost in overtime after head coach Mike Smith decided not to punt on fourth down — Gingrey accused Chu of folding under pressure. The decision to restructure Solyndra's loan "put good money after bad" Gingrey said, and was "not unlike that fateful decision by Mike Smith."

Others in the GOP were more interested in the case's political angles, specifically whether a former fundraiser for President Obama exerted any influence. George Kaiser, who contributed to Obama's 2008 campaign and also invested in Solyndra, must have played some role in the process, alleged Rep. Joe Barton, R-Texas. While Barton said he believes Chu that Kaiser didn't personally pressure him to approve the loan, he added that "everybody and their dog knew who he was," suggesting Kaiser's reputation alone was enough to tip the scales for Solyndra.

Chu countered that he didn't know who Kaiser was at the time, although he does now. Addressing accusations that Kaiser may have leaned on contacts in the White House, Chu added that "we did not communicate with the White House about whether we should approve a loan. ... That was our responsibility."

Barton, along with Tennessee Rep. Marsha Blackburn and other Republicans, assured Chu the hearing wasn't meant to discredit solar power or federal assistance to renewable energy. "I happen to continue to support a loan guarantee program for alternative energy," Barton said, "but I cannot continue to support it if we cannot get assurances that this is a history that is not going to be repeated."

To see Chu's opening testimony in Thursday's hearing, check out the video below:

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Russell McLendon ( @russmclendon ) writes about humans and other wildlife.

Chu: Solyndra 'regrettable,' but not political
The U.S. energy secretary spent five hours Thursday rejecting accusations that politics influenced a 2009 loan to the California solar company.