WASHINGTON, March 16 (Reuters) - The U.S. House of Representatives on Tuesday overwhelmingly approved a 60-day extension, to May 31, of the Paycheck Protection Program that helps small businesses stay afloat during the coronavirus pandemic.

The program, launched a year ago as part of a major COVID-19 aid bill, set loans for small businesses such as restaurants that were struggling as the United States went into a lockdown in an attempt to stop the spread of the coronavirus.

Nevertheless, millions of jobs have been lost in small and large businesses and more than 536,000 Americans have died from the highly-contagious disease.

Under the program, loans are converted to grants if businesses meet the program's requirements.

The House approved the extension on a 415-3 vote.

PPP has "provided a lifeline to 'mom and pop' businesses across the country, including those in my district, who are simply trying to survive an unprecedented health and economic crisis," said Democratic Representative Carolyn Bourdeaux of Georgia.

Representative Blaine Luetkemeyer, the senior Republican on the House Small Business Committee, said some businesses have experienced delays in processing grant applications, which would not be resolved before the program expires on March 31.

Addressing that problem, the bill also would set a 30-day period beyond May 31 for the Small Business Administration to finish processing the loans. (Reporting by Richard Cowan and Tim Ahmann; Editing by Michael Perry)