With Speaker Nancy Pelosi (D-Calif.) pressing to pass climate legislation by the July Fourth recess, key House committee chairmen will face crucial tests this week that will determine how much impact they’ll have on the landmark global warming bill.

“We don’t have much time to discuss it, and we’re under the hammer,— Ways and Means Chairman Charlie Rangel (D-N.Y.) said.

His remarks came after Pelosi threw down the gauntlet last week by telling committee chairmen they would have two weeks to weigh in on the bill, already approved by the Energy and Commerce Committee.

The Speaker later softened her remarks and said she would not set a deadline for the chairmen if they were making progress. During remarks Friday at a Brookings Institution event, she said that “it could be this year— that Congress is able to pass climate change legislation into law.

Still, Pelosi’s message got through and caused some chairmen to hasten their efforts on the climate change bill, while others now are expected to hold off on seeking to change or add onto the 1,000-page bill.

The eight other House committees with some oversight over climate change are Foreign Affairs, Financial Services, Education and Labor, Science and Technology, Transportation and Infrastructure, Natural Resources, Agriculture, and Ways and Means. The bill would establish the first federal limits on carbon emissions and mandate expanded production of renewable energy.

Among the most active chairmen have been Rangel and Agriculture Chairman Collin Peterson (D-Minn.), who met several times late last week with the bill’s sponsors; Energy and Commerce Chairman Henry Waxman (D-Calif.); and Subcommittee on Energy and the Environment Chairman Ed Markey (D-Mass.).

Rangel’s committee would have significant sway over tax and other funding provisions in the bill, while members of Peterson’s panel want to ensure farming interests are protected.

Rangel conceded two weeks could truncate his committee’s work on the bill — which may include provisions seeking rebates for low- and middle-income families hit by higher utility bills and guidelines for allocating pollution credits for carbon emitters — and would likely force him to skip a formal markup of the legislation.

Republican Ways and Means members sharply oppose that plan and say committee rules require a markup if substantial tax provisions are added.

Rangel has also made it clear that he considers a health care overhaul bill his panel’s main focus in the coming weeks.

“The truth of the matter is, health care is still a priority,— he said. “And if climate control cannot be smoothly done, then health care is still a priority. But that doesn’t mean climate control cannot be done before health care.—

Shortly after Energy and Commerce approved the bill, Peterson won support from 40 to 45 Democratic Members, including 29 on his committee, to oppose the cap-and-trade legislation. Peterson has since backed away from trying to stop the bill and requiring a markup but insists he wants to “resolve— all pertinent issues.

Other committee chairmen seem less inclined to weigh in.

Education and Labor Chairman George Miller (D-Calif.), a close Pelosi ally, has said his panel would not mark up the bill.

Natural Resources Chairman Nick Rahall (D-W.Va.) also had shown some interest in tacking on provisions altering oil and gas drilling polices on federal lands but now has said that seems unlikely.

Energy and Commerce member Rick Boucher (D-Va.), who helped negotiate changes sought by Democratic moderates, said there are several ways chairmen could still influence the bill.

Boucher said chairmen may settle issues behind closed doors and then attach a manager’s amendment to the bill. Or, he said, they could simply write their changes into the bill. Another option would be to agree to floor amendments, clear them with Pelosi, and add them during floor debate.