U.S. Sen. John Kerry of Massachusetts is urging federal officials to approve a key portion of Cape Wind's financing plan.

Kerry and all 10 Massachusetts members of the U.S. House sent a letter Thursday to Energy Secretary Steven Chu asking that he speed Cape Wind's loan guarantee application so work can begin on the 130-turbine wind farm in Nantucket Sound.

Kerry says a timely approval will reduce the cost of electricity from the nation's first offshore wind farm.

Under a 15-year power purchasing agreement between National Grid and Cape Wind Associates, 75 percent of the savings from a federal loan guarantee would be passed along to customers in the form of lower rates.

Kerry says that translates into millions in savings.

The company hopes to start construction by the end of the year.