WASHINGTON- Negotiations in the U.S. House of Representatives on how to cut industrial pollutants that cause global warming reach a critical stage this week as President Barack Obama huddles with key lawmakers on Tuesday and Republicans ready for a fight.

A House Energy and Commerce panel hopes to fill in details later this week on a bill that aims to cut emissions of carbon dioxide and other greenhouse gases 20 percent by 2020 and 83 percent by 2050 -- using 2005 as a base year.

A White House official said the meeting between Obama and some Democratic members of the panel would review provisions being negotiated by lawmakers, as well as the timetable for moving the controversial legislation through the House.

Various sources are telling us progress is being made in the (negotiating) room, said Manik Roy of the Pew Center on Climate Change, which supports cap and trade legislation that would impose the new limits on pollutants.

Tony Kreindler, of the Environmental Defense Fund, added lawmakers were still very much in the thick of the negotiations.

Aides to key lawmakers would not provide details on the negotiations, which continued over last weekend.

Eben Burnham-Snyder, a spokesman for Representative Edward Markey, would not say whether a key subcommittee will convene this week to fill in details of the bill. Markey, along with House Energy and Commerce Chairman Henry Waxman, is leading the drive.

Waxman told reporters outside the House of Representatives Monday evening that there was not yet agreement on a climate bill. We haven't reached an agreement that makes everybody comfortable, he said. He expected that Obama, in the Tuesday meeting, would urge us to keep working.

The goal of cap and trade, a system that has been successfully used to control acid rain pollution in the northeastern United States, is to encourage industries to use energy sources that emit less carbon dioxide and other greenhouse gases. Those sources could be wind, nuclear and solar power and other alternative energy, as well as cleaner coal that supporters hope can be developed.

As overall limits on carbon pollution fall, utilities, steel companies and others that still pollute more than their limit could buy credits from firms that pollute less so that their operations can continue while they work on ways to become cleaner.

With many Democrats nervous about voting for a bill that Republicans are calling a new national energy tax, the meeting with Obama likely will be aimed in part at assuring those lawmakers that the popular president will stand behind them.

REPUBLICAN AMENDMENTS

Cristie Greco, a spokeswoman for House Majority Whip James Clyburn, said there was a positive and productive meeting last week between Waxman and Clyburn over including help for the nuclear energy industry in the bill.

Former President George W. Bush, urged on by some industry groups, opposed U.S. participation in global efforts to cut greenhouse gas emissions. Many House Republicans are carrying on that fight, saying the Democrats' climate-change bill will hurt consumers at a time when the United States is struggling with an economic recession.

American families are struggling to make ends meet, yet Democrat leaders in Washington want to tax them for using the only energy sources available to them, said Representative Tom Price of Georgia, who heads a group of House conservatives.

Democrats have countered that they will try to reimburse consumers for higher energy costs associated with reducing carbon emissions. Those higher costs could hit Midwestern and Southeastern states, which rely heavily on coal to drive electricity production, particularly hard.

According to lobbyists and congressional aides, House Republicans have prepared well over 100 amendments to the bill, which likely would slow committee work on it.

Still unknown was whether Waxman and Markey had successfully negotiated demands by some fellow Democrats that all or a portion of pollution permits be given to U.S. industries, instead of sold to them.

Giving away the credits would save polluters money at first. But some opponents fear firms might raise energy rates on consumers anyway while at the same time holding permits that will gain value for them in the future if they want to trade them away.

American Petroleum Institute senior policy analyst Lou Hayden said no deal is imminent between lawmakers on how to allocate carbon permits to oil refineries.

The Edison Electric Institute, a utility trade group, has been lobbying lawmakers to initially provide 40 percent of pollution permits to power plants at no cost before gradually transitioning to a full auction.

EEI spokesman Jim Owen said he did not know what the final language of the cap and trade bill would be, but our point of view does seem to be gaining some traction.

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