WASHINGTON — The Biden administration on Thursday announced plans to develop floating platforms in the deep ocean for wind towers that could power millions of homes and vastly expand offshore wind in the United States.

The plan would target sites in the Pacific Ocean off the California and Oregon coasts, as well as in the Atlantic in the Gulf of Maine.

President Joe Biden hopes to deploy up to 15 gigawatts of electricity through floating sites by 2035, enough to power 5 million homes. The administration has previously set a goal of 30 GW of offshore wind by 2030 using traditional technology that secures wind turbines to the ocean floor.

There are only a handful of floating offshore platforms in the world — all in Europe — but officials said the technology is developing and could soon establish the United States as a global leader in offshore wind.

The push for offshore wind is part of Biden’s effort to promote clean energy and address global warming. Biden has pledged to cut greenhouse gas emissions in half by 2030. A climate-and-tax bill he signed last month would spend about $375 billion over 10 years to boost electric vehicles, jump-start renewable energy such as solar and wind power and develop alternative energy sources like hydrogen. ...