The legislation would require the U.S. to reduce carbon dioxide and other greenhouse gas emissions by 17 percent from 2005 levels by 2020 and by about 80 percent by mid-century. That was slightly more aggressive than Obama originally wanted, 14 percent by 2020 and the same 80 percent by mid-century.

U.S. carbon dioxide emissions from the burning of fossil fuels are rising at about 1 percent a year and are predicted to continue increasing without mandatory limits.

Under the bill, the government would limit heat-trapping pollution from factories, refineries and power plants and issue allowances for polluters. Most of the allowances would be given away, but about 15 percent would be auctioned by bid and the proceeds used to defray higher energy costs for lower-income individuals and families.

"Some would like to do more. Some would like to do less," House Majority Leader Steny Hoyer, D-Md., said in advance of the final vote. "But we have reached a compromise ... and it is a compromise that can pass this House, pass that Senate, be signed by the president and become law and make progress."

That seemed unlikely, judging from Reid's cautiously worded statement. "The bill is not perfect," it said, but rather "a good product" for the Senate to begin working on.

And there was plenty to work on in a House-passed measure that pointed toward higher electricity bills for the middle class, particularly in the Midwest and South, as well as steps to ease the way for construction of new nuclear reactors, the first to be built since the accident at Three Mile Island in 1979.

The bill's controversy was on display in the House, where only eight Republicans joined 211 Democrats in favor, while 44 Democrats joined 168 Republicans in opposition. And within an hour of the vote, both party campaign committees had begun attacking lawmakers for their votes.

One of the biggest compromises involved the near total elimination of an administration plan to sell pollution permits and raise more than $600 billion over a decade — money to finance continuation of a middle class tax cut. About 85 percent of the permits are to be given away rather than sold, a concession to energy companies and their allies in the House — and even that is uncertain to survive in the Senate.

The final bill also contained concessions to satisfy farm-state lawmakers, ethanol producers, hydroelectric advocates, the nuclear industry and others, some of them so late that they were not made public until 3 a.m. on Friday.

Supporters and opponents agreed the bill's result would be higher energy costs but disagreed vigorously on the impact on consumers. Democrats pointed to two reports — one from the nonpartisan Congressional Budget Office and the other from the Environmental Protection Agency — that suggested average increases would be limited after tax credits and rebates were taken into account. The CBO estimated the bill would cost an average household $175 a year, the EPA $80 to $110 a year.

Republicans questioned the validity of the CBO study and noted that even that analysis showed actual energy production costs increasing $770 per household. Industry groups have cited other studies showing much higher costs to the economy and to individuals.

It will "make our nation the world leader on clean energy jobs and technology," declared Rep. Henry Waxman, D-Calif., who negotiated deals with dozens of lawmakers in recent weeks to broaden the bill's support.