NRG Energy executives said Monday they will cut monthly investment in new nuclear plants by 95 percent until the U.S. government gets moving on loan guarantees.

Chief executive David Crane said he worries it could take another year for the government to award the guarantees. He said cutting spending now won't necessarily delay the building of two reactors at the South Texas Project.

"We just literally have no idea when the U.S. government will do the two things – the Department of Energy actually finish the loan guarantee process, hopefully in a positive fashion, and the money be appropriated," Crane said during a conference call Monday.

"This uncertainty about when is what makes it impossible for me to continue spending NRG shareholders' money at the rate which we have been spending," he said.

NRG is one of several companies that are pursuing loan guarantees. The government has already awarded a loan guarantee to one project, and NRG is among the finalists to win another guarantee. Government officials haven't said exactly how many projects they will fund.

Last month, NRG cut its spending to $7.5 million from about $30 million. As of Aug. 1, the company will spend only $1.5 million a month on the project that has been planned for years.

The Nuclear Regulatory Commission hasn't yet awarded NRG a license to build or operate the plant, so NRG cannot build the reactors yet. The company may prepare the site, order the equipment and negotiate financing and electricity pricing with customers.

NRG executives had expected San Antonio's municipal electricity company, CPS, to invest in the project, but the city pulled out.

Crane has said NRG cannot build the reactors unless the U.S. government provides guarantees for the loans. But he said Monday: "I am more confident than I have ever been that our project ultimately will be awarded a nuclear loan guarantee from the United States government."