The House is heading for a showdown vote this week on landmark global warming legislation and Democratic leaders are still scrambling to line up support among pockets of resistance in their own party.

Despite intense negotiations by the measure’s architects to woo rural and coal states with concessions on issues important to them, the kind of opposition the bill still faces was illustrated by Rep. Earl Pomeroy , D-N.D., a member of the Agriculture Committee as well as the fiscally-conservation Blue Dog coalition.

Pomeroy, whose state has both rural and coal interests, said it could face a double whammy from legislation that puts a price on fossil fuel emissions.

“I will vote no,” Pomeroy said Wednesday evening. “My response is to vote the interests of North Dakota. We’re about the fourth most energy-consumptive state in the country.”

On a per capita bases, energy use in Pomeroy’s state is one of the highest in the nation, mostly because of winter heating needs, according to the Energy Information Administration, the statistical arm of the Energy Department.

Pomeroy said he doubted whether the other Agriculture committee members would also go along as easily as expected.

Massachusetts Democrat Edward J. Markey , a point man for House Energy and Commerce Committee Chairman Henry Waxman, D-Calif, met Wednesday evening with several of those Agriculture members, in an effort to change their minds.

Markey also met with a bloc of upstate New Yorkers, who remain uncommitted for a variety of reasons, including concerns about how the bill distributes pollution allowances to coal-fired power plants.

Ohio Democrats are also proving a tough sell because they fear that the emissions rules could harm manufacturers, especially of energy-intensive products such as steel. Waxman and House Speaker Nancy Pelosi , also of California, met Wednesday with undecided Ohio Democrats Betty Sutton , John Boccieri , Mary Jo Kilroy , Marcia L. Fudge and Marcy Kaptur .

Meanwhile, while awaiting action in the House, Senate Democrats are trying to broker a similar consensus in their chamber.

Senate Majority Whip Richard J. Durbin , D-Ill., said senators want to build on whatever the House does.

“There’s a term in car racing: drafting,” he said. “If you’re being pulled along in the wind behind another car, you’re drafting. We’re drafting behind the House. Their success or failure will really determine what we can do.”

A group of about 25 Senate Democrats, led by Environment and Public Works Chairwoman Barbara Boxer of California, has been following efforts by House leaders to win over moderate Democrats from Midwestern farm and industrial states.