By Jessica Brady, CQ-Roll Call

President Obama may be heading to Copenhagen next month for the United Nations’ global climate change summit, but Democratic senators tasked with moving health care overhaul legislation will likely stay behind to pass a bill by year’s end.

About a dozen senators had been expected to attend the 11-day forum, but that was before Democratic leaders planned to spend the entire month of December debating — and voting on — a sweeping health care package. And since Majority Leader Harry Reid , D-Nev., needs every vote he can get to stave off GOP amendments and pass a final measure, it will be difficult for lawmakers to leave town while the Senate is in session and voting.

So while several administration officials — EPA Administrator Lisa P. Jackson , Council on Environmental Quality Chairwoman Nancy Sutley and Carol Browner, assistant to the president for energy and climate change — will join Obama in Denmark’s capital, Finance Chairman Max Baucus , D-Mont., will be on the Senate floor overseeing the health care debate. Other leading Democratic senators whose committees have jurisdiction over climate change may also face scheduling difficulties. Among them: Environment and Public Works Chairwoman Barbara Boxer of California; Commerce, Science and Transportation Chairman John D. Rockefeller IV of West Virginia; Energy and Natural Resources Chairman Jeff Bingaman of New Mexico; Agriculture, Nutrition and Forestry Chairman Blanche Lincoln of Arkansas; and Foreign Relations Chairman John Kerry of Massachusetts.

Despite the potential conflicts, Boxer and Kerry, who are cosponsoring the Senate’s leading climate change bill, are still holding out hope they can make the trip. The forum is expected to draw an estimated 60 world leaders to draft a set of environmental guidelines to reduce greenhouse gas emissions. “This could be one hell of a global game-changer with big reverberations here at home,” Kerry said Wednesday of Obama’s announced trip, which “lays the groundwork for a broad political consensus at Copenhagen.”

Rep. Edward J. Markey , D-Mass., chairman of the House Energy and Commerce Subcommittee on Energy and Environment, has a ticket booked for Copenhagen and called Obama’s voyage “the most significant travel reservations ever made.”

Unlike the House, which passed climate change legislation June 26 by a 219-212 vote, senators have been unable to reach consensus on the issue. Democratic leaders are hoping to tackle climate change next year in the Senate, but that goal may be difficult to achieve given the political realities of an election year. House members also have less pressure on the health care front given they narrowly passed an overhaul on Nov. 7.

Reid has said he’d like to pass a bill before Christmas.

Republicans are equally engaged in health care, but don’t face the same pressure as Democrats, who will need to keep all 60 members aligned to control the debate. With that in mind, several GOP senators are taking their opposition to cap-and-trade legislation to Copenhagen. James M. Inhofe of Oklahoma, the ranking Republican on the Senate Environment panel, will lead a “truth squad” to the summit, which will feature Sen. John Barrasso , R-Wyo., among others.

Also expected are top administration officials such as Interior Secretary Ken Salazar , Agriculture Secretary Tom Vilsack , Commerce Secretary Gary Locke and Energy Secretary Steven Chu , each of whom will “keynote a series of events highlighting actions by the Obama Administration to provide domestic and global leadership in the transition to a clean energy economy,” according to a White House release.

Speaker Nancy Pelosi , D-Calif., has remained noncommittal on her Copenhagen plans, as has House Energy and Commerce Chairman Henry A. Waxman , D-Calif., one of Pelosi’s top lieutenants on both health care and climate change.

The summit runs from Dec. 7-18. Obama announced Wednesday that he will join the conference on Dec. 9.