Sen. Jeff SessionsJefferson (Jeff) Beauregard SessionsDOJ requests military lawyers to help prosecute immigration crimes: report Trump backs down in rare reversal Senate moving ahead with border bill, despite Trump MORE (R-Ala.) and Rep. Darrell Issa (R-Calif.), the chairman of the House Oversight Committee, sent a letter to Secretary Ken Salazar requesting communications that included a number of Interior Department staffers. Issa and Sessions want the records in order to determine whether the Interior Department gave preferential treatment to certain energy companies.

"We are writing to request information that the Department of the Interior (DOI) has thus far refused to provide to Congress," the legislators write in the letter sent Tuesday. "More than six months ago Senator Jeff Sessions, the Ranking Member of the Senate Committee on the Budget, requested specific information regarding DOI's possible preferential treatment of certain renewable or alternative energy projects — all of which received taxpayer loan guarantees. Despite repeated attempts to have this request fulfilled, DOI has not produced an adequate response. This is unacceptable."

Specifically, Sessions and Issa want communications records that include David Hayes, the deputy secretary of the Interior; Steve Black, an adviser to Salazar; Janea Scott, special assistant to the counselor to the Department of the Interior; Ned Farquhar, deputy assistant secretary for land and minerals management; and Neil Kornze, deputy director of the Bureau of Land Management.

Sessions and Issa also want any communications that involved six specific energy companies: Abengoa Solar, Inc., BrightSource Energy, First Solar, Inc., Nevada Geothermal Power, Inc., NextEra Energy Resources and SolarReserve, LLC.

The letter falls in line with Republican criticism of Solyndra, the California solar panel manufacturer that received a $535 million Energy Department loan guarantee in 2009 but went bankrupt in 2011. Republicans pounced on the company's collapse to allege that the White House had recklessly spent taxpayer money on environmental projects. Republicans have also sought to show that the support for Solyndra was politically motivated to aid donors to the president, but an in-depth House GOP probe failed to show political favoritism.

The letter from Issa and Sessions suggests Republicans might now plan on extending that criticism to the Department of the Interior, where Salazar has regularly highlighted efforts to expand renewable energy use on federal land. Sessions and Issa had previously called on Salazar to release the records six months earlier.

—Ben Geman contributed reporting.

Read the letter below:

Sessions Issa Letter to Salazar