Republicans on a House Energy and Commerce Committee panel on Thursday overrode vigorous Democratic objections and took the apparently unprecedented step of authorizing subpoenas for internal White House communications related to a half-billion-dollar taxpayer loan guarantee for the failed solar company Solyndra.

The move followed a last-minute attempt by the White House to fend off the move, with officials meeting with committee members and delivering several boxes of e-mails and other documents to committee investigators on Wednesday afternoon.

Rep. Diana DeGette (Colo.), ranking Democrat on the panel, called it a “sad day” for the committee and “an act of irresponsible partisanship,” stressing that the committee had never before subpoenaed the White House. She noted the administration had already turned over thousands of pages of documents and said a subpoena should be issued only after all alternative routes have been abandoned.

Republicans said they had hoped to avoid the step, but that the committee’s long-running investigation had failed to get to the bottom of why Solyndra, which collapsed in August and is now under criminal investigation, was selected to receive the Obama administration’s first loan guarantee under the stimulus act. President Obama last year visited the company’s California operation, whose biggest investors were venture capital funds linked to Tulsa billionaire George Kaiser, a major Obama fundraiser.

Some Republicans have questioned whether the administration rushed stimulus funding out the door to benefit its political supporters. On Oct. 14, the White House told the committee that it would not comply with a request for all internal White House communications regarding the Solyndra loan.

Following the vote, a White House official said the administration had cooperated extensively with the committee’s investigation, producing more than 85,000 pages of documents, including 20,000 pages Thursday afternoon, and having administration officials provide multiple briefings and hearings.

“The White House has also already provided over 900 pages of documents in response to requests we have received. And all of the materials that have been disclosed affirm what we said on day one: This was a merit-based decision made by the Department of Energy,” White House spokesman Eric Schultz said.

“We’d like to see as much passion in House Republicans for creating jobs as we see in this investigation. The White House has been clear with the committee that we are willing to cooperate with legitimate oversight requests that are tailored to balance the important institutional interests of both branches. We are disappointed that the committee has refused to discuss their requests with us in good faith, and has instead chosen a partisan route, proceeding with subpoenas that are unprecedented and unwarranted.”

“I regret that we have reached this place,” Rep. Cliff Stearns (R-Fla.), chairman of the subcommittee on Oversight and Investigations, said Thursday morning at a meeting of the panel. “The committee has been investigating this for over eight months and has clearly established the legitimacy of our investigation. Two of the first three companies to receive loan guarantees have now filed for bankruptcy protection.

“The committee needs to better understand what the White House’s involvement was with regard to Solyndra’s loan guarantee. If the White House has nothing to hide, they should cooperate with this investigation and produce the documents. I believe the president owes it to the American people to explain in detail what happened to their tax money.”

Committee Chairman Fred Upton (R-Mich.) said that Republicans “smelled a rat from the beginning” and that the probe had clearly established that red flags about problems at the company were ignored, both with the initial loan guarantee and with a restructuring of loan terms in February.

“We have clearly established that senior White House advisers had close knowledge of the Solyndra loan and that DOE officials felt pressure from the White House to approve the loan,” Upton said. “The White House has refused to produce them, and we have no choice but to authorize the issuance of a subpoena to compel them.”

The final terms and scope of the subpoena were still to be finalized. Democrats complained that the broad language of the approval might allow Republicans to demand the contents of messages from the president’s personal BlackBerry.

Energy Department officials said the loan was approved on its merits and that it was a good bet at the time it was made. They said political influence played no part in its decisions.

Democrats argued that the White House was doing its best to comply with investigators, but that requests so far had been overly broad and, in the words of Rep. Henry Waxman (D-Calif.), “a fishing expedition” that “looks more like a rigged process.”

Waxman charged the Republican were not looking for the truth but instead seeking a confrontation with the administration.

“This is no way to run an investigation. It is an unprecedented departure from the practices of this committee,” Waxman said,

Also on Thursday, the chairman of the House Committee on Oversight and Government Reform, Rep. Darrell Issa (R-Ca.), released a letter he sent to Energy Secretary Steven Chu saying that he would use “compulsory measures” if the department did not more fully respond to his committee’s investigation into a series of other loan guarantees.

Solyndra, a Silicon Valley solar panel maker, was a centerpiece of Obama’s initiative to develop clean energy technologies and received the program’s first loan guarantee, for $535 million. Solyndra reported accelerating sales until Aug. 31, when it collapsed and filed for bankruptcy protection.

The collapse has become a political liability for the White House because of ties to Kaiser. At the White House, records show Kaiser has met with presidential adviser Valerie Jarrett and Rahm Emanuel, who was then Obama’s chief of staff. Kaiser has said he did not lobby on behalf of Solyndra or help it win its loan guarantee.

Thursday’s action by the energy panel marked the second time the committee has subpoenaed the Obama administration for Solyndra documents. In July, the investigations panel sought documents from the Office of Management and Budget related to the 2009 loan guarantee. That request produced records showing interest in the loan extended to senior White House officials, especially concerning the timing of its announcement.

Also Thursday, Rep. James Sensenbrenner (R-Wis.) introduced a bill to require independent audits of all renewable-energy loan guarantees as well as independent review for all future loans.

“The administration did not even begin to examine this billion-dollar sinkhole until after the stimulus deadline had passed,” Sensenbrenner said. “I doubt their thinly-veiled attempt at image management will be a sufficient cure for the diseased loan guarantee program.”

The act would require an assessment of all past renewable-energy loan guarantees, loans, grants, and direct payments, as well as an independent review of all future renewable-energy loan guarantees. A similar bill is pending in the Senate.

As the House panel voted Thursday, Chu defended his programs under questioning before an energy conference.

“As we look at what happened in Solyndra, … hindsight is often said to be 20/20. In this case, I think some of the hindsight was 20/10 or even better — clairvoyant,” Chu said at the Washington Post Live Smart Energy Conference in Washington.

“There were things that where the market took an unexpected turn -- the cost of solar modules dropped tremendously in a very short period of time, and in the time we gave the loan; totally unexpected. We were watching all those market conditions. But going forward, I think knowing what we knew at the time doing these things, I think one has to take risks in order to promote innovative manufacturing.

“My message to Congress is more along the same lines of what I said here today, that this is a key time in American history. There is key opportunity, to seize the opportunity, to not walk away when there’s a stumble. You can learn from those and keep going, because this is the direction I believe, the president believes, the administration believes is the direction which is key to our job creation today and our future prosperity.”

Issa’s letter to Chu referred to loan guarantees that the department authorized in late September on the day the program’s funding was set to expire. On Sept. 30, the agency committed $4.7 billion in stimulus funds to projects led by SunPower, Exelon, NRG Energy, and a joint partnership led by NextEra and a General Electric subsidiary.

“The incomplete response from the Department of Energy is unacceptable considering the amount of time that has elapsed since the request,” Issa wrote in the letter dated Wednesday. He said he would compel the administration to produce the requested documents and correspondence “if DOE continues to refuse to cooperate fully with this investigation.”