Wind turbines lining the Altamont Pass near Livermore, Calif., generate electricity. (Noah Berger/Associated Press)

Wind power advocates urged Congress on Thursday to quickly restore the production tax credit that expired at the end of 2013, saying that a prolonged period without it threatens gains made in recent years.

Officials from a wind power company, a steel company and the American Wind Energy Association said the loss of the 2.3-cents per kilowatt hour tax credit will directly translate into lost jobs. Despite continued demand, steel companies, wind energy firms and utilities will not devote their money and resources to wind power without the certainty that the credit provides, they said.

“We have to have a quick extension” of the credit, said Jaime Steve, director of government affairs at Pattern Energy, which runs wind power projects in the United States, Canada and Chile. “This is about people’s jobs.

“If we lose those people, they don’t come back,” he added. “They go to other industries.”

Congress allowed a variety of tax breaks, worth a total of about $50 billion a year, to expire on Dec. 31. The 2013 production tax credit, designated specifically for wind power, cost $12 billion over 10 years.

Tom Kiernan, chief executive officer of the American Wind Energy Association, attributed a huge decline in the completion of wind power projects last year to the uncertainty caused by a brief expiration of the tax break at the end of 2012 that lasted for the first few days of 2013. By most other measures, including the number of projects under construction and long-term power purchase agreements, wind energy had a very successful 2013.

The number of completed projects should rebound this year because Congress required companies only to begin construction to claim the 2013 tax credit.