The outcome will be a trial of Bush's strength and of the moderates' determination to challenge him on one of his signature issues.
Republican leaders hope to keep the bill as intact as possible, knowing it will have to be reconciled with a Democrat-written Senate bill this year. If the moderates prevail, they could significantly undermine Bush's drive to increase domestic oil production, the central thrust of his energy plan.
Environmental and business groups are working hard on both sides of the debate, running television ads in Washington and lobbying Congress. Bush himself is expected to try to bring wavering Republicans to his side.
"In its present state, the energy bill would be in serious trouble on the floor," said Rep. Sherwood Boehlert (R., N.Y.), one of the leading GOP environmentalists in the House and chairman of the Science Committee.
So far, Republican centrists have won some small victories, including amendments to spending bills that blocked oil drilling on certain public lands and under the Great Lakes and that prevented the Bush administration from rolling back a tough new standard for acceptable levels of arsenic in water. But they have yet to prevail on bigger initiatives such as campaign finance, a so-called patients' bill of rights, and a bill that allowed church groups to use federal money to provide social-welfare programs.
The energy bill may be their first chance to significantly shape a large piece of legislation.
"Are we doing more for conservation?" asked Rep. Mark Foley, a Republican moderate from Florida. "Are we doing enough for renewables, for solar and wind energy? Are we making sure that our view is a long-term view, not just finding more oil?"
