Senate committee action on climate change legislation will be delayed until September, giving negotiators and their aides an extra month to work on the controversial legislation.

Environment and Public Works Committee Chairwoman Barbara Boxer , D-Calif., said Thursday she no longer intends to mark up the bill before the Senate leaves for its summer recess Aug. 7. Instead, she said, she will set the markup for early September.

Boxer and the chairmen of other committees that share jurisdiction over the complex legislation met Wednesday evening with Majority Leader Harry Reid , D-Nev., and Carol M. Browner, White House coordinator of energy and climate policy. Reid agreed to extend to Sept. 28 his original Sept. 18 deadline for all committees to finish their work on the bill.

The delay will give Boxer more time to work on legislative text, which she previously said to expect “in a matter of days.” Her bill will be modeled on legislation that narrowly passed the House in June, which would cap greenhouse gas emissions that lead to global warming and create a system for buying and selling emissions permits. But Boxer will likely have to make significant changes to the House bill in order to win support for her measure even among Democrats.

She insisted the delay will not stop the Senate from finishing the bill this year: “We’ll be in until Christmas,” she predicted.

One factor contributing to the delay in moving climate change legislation is the competition from health care legislation. Boxer noted several senators with a role in the climate change debate also are engaged in writing the health bill.

“We’re all so busy on health care, and we want to get some numbers back that help us in terms of explaining [the bill] to people,” said John Kerry , D-Mass. “It’s purely procedural.”