By John M. Broder New York Times News Service

WASHINGTON — This was to have been the year that Congress finally took meaningful action to address the related problems of energy dependence and global warming. The new Democratic majority vowed to make these issues a top priority, President Bush spoke of ending America’s addiction to imported oil and industry groups promised to do their share to build a cleaner and more efficient future.

All this will come to a test today when the House debates a 786-page energy bill that could be a major leap toward the twin goals polls say most Americans have come to embrace: reducing reliance on dirty-burning fossil fuels and slowing global warming.

But the House Democratic leadership blinked on the issue of setting tough new automobile and truck mileage rules, deferring the question to a conference committee with the Senate later this year. The fate of a second major provision, requiring most electric utilities to produce 15 percent of their power from renewable sources, remains uncertain.

The energy bill — actually an amalgam of bills from a half-dozen House committees — contains a number of significant provisions on energy efficiency for appliances and buildings, incentives for production of alternative fuels, millions of dollars for new research on capturing carbon emissions from refineries and coal-burning power plants and the repeal of some tax breaks for oil and gas producers.

But even supporters of those measures say the bill will fall short without a renewable electricity mandate and stringent new mileage standards for cars and trucks, popularly known as CAFE, for corporate average fuel economy.

“The energy bill ? What energy bill ?” said Dan Becker, director of global warming programs for the Sierra Club and an advocate for more efficient vehicles from Detroit. “If you add everything else in the bill together, it doesn’t equal what you would get from a 35 mpg CAFE standard.”

Speaker Nancy Pelosi made a tactical decision Wednesday to put off the mileage debate rather than provoke a fierce fight among Democrats.

But Pelosi decided to allow debate on the renewable electricity mandate, despite opposition among members from many parts of the country, particularly the Southeast, that lack ready access to wind, solar and hydroelectric power.