A bill to subsidize development of what could be the nation’s first Atlantic offshore wind farm — one of Gov. Martin O’Malley’s signature initiatives — won approval Friday in the Maryland House of Delegates.

The bill, which passed overwhelmingly after an hour-long debate, now heads to the Senate.

The plan would add a fee to every Marylander’s monthly electric bill for 20 years and thousands of dollars to the bills of the state’s largest businesses to construct a multibillion-dollar offshore wind farm off the coast of Ocean City.

O’Malley (D) has argued the plan would create about 2,000 jobs and give Maryland a leg up on neighboring states in a new green-energy market.

A similar bill failed to gain momentum last year, when lawmakers raised questions about how much of the cost and risk ratepayers would be asked to shoulder.

Wind turbines whirl off of Denmark in 2001. (SOEREN BIDSTRUP/AFP/Getty Images)

O’Malley returned this year with a bill that would cap the average monthly cost to residents at $2. But in negotiations with lawmakers, the administration agreed to lower the monthly subsidy charged to residential customers to $1.50. The fee on large commercial and industrial users was lowered by 40 percent, to 1.5 percent of their electrical bill.

The fee would not be added to residents’ bills until at least 2017, the earliest date the administration expects an offshore wind farm would be in operation.

But Republicans, who blasted the bill as politically motivated, said it would still place too much of a burden on ratepayers and add to an array of tax and fee hikes O’Malley has proposed this session.

“As we’re getting ready to raise income taxes and raise flush fees and raise everything else, we’re going to kick them again with a little surcharge so that we can deliver a wind bill and a photo-op under great political pressure,” said House Minority Leader Anthony J. O’Donnell (R-Calvert).

Del. Dereck E. Davis (D-Prince George’s), chairman of the committee that backed O’Malley’s plan, disputed suggestions that he had been pressured.

“You guys know me. Nobody can pressure me into a darn thing. I’m a grown man,” Davis said.

Del. Brian K. McHale (D-Baltimore), a committee member, also denied O’Malley had pressured the panel to advance the legislation. “There was pressure on this bill, and the pressure came from the committee to the administration to make sure that this bill is so much different from last year’s bill,” he said.

Del. Benjamin F. Kramer (D-Montgomery), who was unconvinced last year but threw his support behind this year’s bill, said ratepayers would not see any fee increase “until the offshore wind facility is built, operating and producing electricity.”

“If those turbines collapse into the sea, it will not cost the ratepayers a nickel,” he said.

Administration officials said they believed the smaller subsidy could support a wind farm of about 40 turbines that would produce 200 megawatts annually. That would be less than half of what O’Malley sought when he first introduced the idea before the 2011 legislative session.