Key Senate Democrats insisted that they are making incremental progress on a comprehensive global warming bill as they returned to Capitol Hill yesterday following a monthlong break where health care reform surged to the top of Congress' legislative agenda.

Environment and Public Works Chairwoman Barbara Boxer (D-Calif.) told reporters she has made "many decisions" on the climate legislation in recent weeks but declined to elaborate on specifics ahead of a bill introduction later this month with Foreign Relations Chairman John Kerry (D-Mass.).

"You will find out soon enough, as soon as we have our press conference on the bill," Boxer said. "But it is going well."

Boxer also would not say when she would hold a markup, though Senate aides say they are penciling in the EPW Committee vote for early to mid-October. "The bill will be introduced this month and then, immediately following, we will have a markup," Boxer said.

Kerry and Boxer originally intended to roll out their bill this week and finish markups by Sept. 28. But Boxer and Kerry bumped back that schedule last week to continue a series of consultations with government experts who have been modeling their proposal.

"We're burning and churning with CBO and with the EPA," Kerry said. "We're just running by them. The minute you nix something here, or change something, you change the overall formula and outcomes. And we need to know what the costs are, and what the impacts are."

Kerry also declined to talk timelines. "I'm not going to make a prediction on a date, so we don't fall short of something," he said. "But obviously, we're trying to move it as fast as we can this month."

Senate aides said Kerry also plans to meet in the coming weeks with fence-sitting Senate Democrats and Republicans to try and expand the coalition supporting the bill should Majority Leader Harry Reid (D-Nev.) follow through with plans to give it floor time later this year.

Other small signs of progress are coming from some of the moderate Senate Democrats who have been working on their own for several months on issues considered critical to finding the 60 votes necessary for final passage.

Sen. Tom Carper (D-Del.), a senior member of the EPW Committee, told reporters yesterday that he is nearing a resolution with a small group of coal-state Democrats on coal research and technology issues.

"We're pretty close to having something constructive," Carper said, declining to discuss details. Senate aides said Carper's working group, organized earlier this spring by Boxer, includes Sens. Max Baucus of Montana, Robert Byrd of West Virginia and Arlen Specter of Pennsylvania.

Separately, Sen. Sherrod Brown (D-Ohio) said a group of manufacturing-state senators are within a few weeks of unveiling language that spells out how to deal with carbon-intensive U.S. industries. Brown said he is meeting next week with Boxer to go over an agenda that includes allocation of allowances, as well as a "border equalization" option that focuses on developing nations.