WASHINGTON, USA: Republican lawmakers alleged on Friday that the Energy Department used a loan guarantee to a massive rooftop solar project as part of a last-ditch effort to bail out Solyndra, a solar panel maker that later failed.

The Energy Department denied the claims. The White House has said House Republicans are distorting the facts in the interest of politics.

The House Energy and Commerce Committee asked Energy Secretary Steven Chu to provide internal documents about the relationship between Solyndra and "Project Amp," the largest U.S. project to install solar panels on commercial rooftops.

"We have questions about Solyndra's involvement in Project Amp, and what role Solyndra's involvement played in DOE's decision" to give the rooftop project a loan guarantee, U.S. Republican Representative Fred Upton, chairman of the Energy and Commerce Committee, and U.S. Republican Representative Cliff Stearns, who is leading the probe, said in a letter to Chu.

It's the latest twist in the Republicans' year-long probe into Solyndra, which filed for bankruptcy in September 2011 despite receiving a $535 million government loan guarantee.

The California company's failure has been an embarrassment for the White House after President Barack Obama visited the firm in 2010. His administration has promoted clean energy as one way to create jobs.

Republicans have used the failed investment in stump speeches and television attack ads to criticize Obama's energy and economic policies. In their investigation, lawmakers have tried to show that the government should have cut its losses earlier in the project.

The Energy Department denied that a $1.4 billion loan guarantee given to Project Amp was tied to Solyndra.

"As has consistently been the case in the course of this committee's year-long political investigation, critics of our effort to support innovative, job-creating clean energy projects will say anything to distort the record," said Damien LaVera, an Energy Department spokesman.

SOLYNDRA BID TO SUPPLY PANELS

Project Amp is the largest project of its kind in the country, an effort to generate power for the grid from the roofs of warehouses in 28 states.

The buildings are managed by real estate company Prologis, and the project received financial backing from power company NRG Energy Inc and Bank of America Merrill Lynch.

Representatives for Prologis and NRG did not immediately respond to requests for comment, and Bank of America declined comment.

Solyndra bid to supply panels to an early phase of the project. The lawmakers said they have documents that show Energy Department officials were involved in Solyndra's negotiations with Prologis for supplying panels in the weeks leading up to Solyndra's bankruptcy.

The lawmakers are "greatly concerned at the extraordinary measures the Obama administration appears to have taken in keeping Solyndra afloat," the committee said.

The deal was seen as critical to Solyndra achieving its sales targets. Private backers of Solyndra said in e-mails they would only invest more money in the flailing company if the sales contract was finalized, according to the Republicans.

Other documents show Solyndra employees taking an active interest in whether Project Amp would obtain a loan guarantee, the committee said.

Chu was actively involved in propelling Project Amp forward. But a department spokesman said Chu took interest because of the scope and importance of the rooftop solar project.

"Secretary Chu strongly supported Project Amp because it will be the largest rooftop project in U.S. history and is expected to generate enough clean, renewable electricity to power over 88,000 homes while supporting at least 1,000 jobs," department spokesman LaVera said.

Ultimately, Solyndra shut its doors a month before the Energy Department finalized the loan guarantee for Project Amp.

The Energy Department's inspector general - an internal but independent watchdog - has been investigating Solyndra in tandem with the FBI, which raided the company in September.

BITTER BATTLE TO CONTINUE

The Republicans initially focused their investigation on whether the government favored Solyndra because one of its private investors also raised money for Obama's 2008 presidential campaign.

But in recent months, the focus has turned to the intricate details of how and why Solyndra failed. Lawmakers have asked a government procurement agency for details about Solyndra's efforts to secure government contracts.

The Republicans have waged a public fight with the White House, complaining that the Obama administration has not fully responded to its requests. The White House has argued it's all just to score political points.

"After 187,000 pages of documents, nine committee staff briefings, and five congressional hearings, Republicans' allegation of unresponsiveness is as unfounded as their allegation of political favoritism," White House spokesman Eric Schultz said earlier this week.