The House Rules Committee cleared the bill for floor action early Friday after working through most of the night. Debate on the measure, which Republicans largely oppose as too costly, has been set for three hours.
It was still uncertain whether House Speaker Nancy Pelosi has the votes to get the measure through. The bill would impose the first U.S. limits on greenhouse gases linked to global warming and would shift the country away from reliance on fossil fuels.
A handful of undecided Democrats hold the key to passage of the bill that the leadership has sought to act on before Congress departs for a weeklong recess for U.S. Independence Day on July 4.
President Barack Obama, in both individual phone calls and in remarks from the White House Rose Garden on Thursday, urged lawmakers to pass the bill, calling it "a vote of historic proportions ... that will open the door to a clean energy economy" and green jobs.
The president and Pelosi, who has staked her prestige on passage of climate legislation, tried to counter a drumbeat of criticism from Republicans who have characterized the bill as a massive energy tax on every American and a "job killer," especially in energy intensive parts of the economy.
"It will create millions of new jobs," Pelosi insisted at a news conference Thursday. Both Obama and Pelosi preferred to focus on the economic issues rather than on what environmentalists view as the urgency of reducing carbon emissions blamed for global warming.
Jobs and future energy prices is what's on the minds of many of the Democratic holdouts that Pelosi and key sponsors of the bill have been pursuing for support. The Midwestern industrial coal-state Democrats who have been sitting on the fence worry about how to explain their vote for higher energy prices to people back home - and how the vote might play out in elections next year.
Republicans have been quick to exploit those concerns.
"Democratic leaders are poised to march many moderate Democrats over a cliff ... by forcing them to vote for a national energy tax that is unpopular throughout the heartland," Republican leader John Boehner said.
The legislation, totaling about 1,200 pages, would require the country to reduce carbon dioxide and other greenhouse gas emissions by 17 percent from 2005 levels by 2020 and about 80 percent by the next century. U.S. carbon dioxide emissions from the burning of fossil fuels have been increasing at about 1 percent a year and are expected to continue to go up if no mandatory reductions are required.
Under the bill, the government would limit heat-trapping pollution from factories, refineries and power plants and distribute pollution allowances that could be bought and sold, depending on whether a facility exceeds the cap or makes greater pollution cuts than are required.
Everyone agrees that under this "cap-and-trade" system the cost of energy is expected to increase as electricity producers and industrial plants pay for increased efficiency, move toward greater use of renewable energy, pay for ways to capture carbon emissions or purchase pollution allowances.
They disagree, however, on how much of the added cost would be passed onto consumers. Democrats argue that much of the cost increase could be offset by other provisions in the bill.
Two reports issued this week - one from the nonpartisan Congressional Budget Office and the other from the Environmental Protection Agency - seemed to support that argument. They showed household energy costs likely would increase only modestly, with most of the increase erased by improvements in efficiency, energy rebates and pollution allowances to energy-intensive sectors of the economy.
The CBO analysis estimated that the bill would cost an average household $175 a year, while the EPA put it at between $80 and $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 cost to the economy and to individuals.