Republicans boycotted the start of committee debate Tuesday on a bill to curb greenhouse gases, protesting that the bill's costs have not been fully examined. The action put a spotlight on the difficulties Democratic leaders face in moving climate legislation this year.

Republican Sen. George Voinovich attended the session for 15 minutes to explain his party's argument for staying away. He insisted the tactic "is not a ruse" to block the bill, but reflects concern that its widespread impact on the U.S. has not been made clear.

But Sen. Barbara Boxer, a Democrat and the panel's chairman, argued the Environmental Protection Agency already has provided "a full blown economic analysis" and that Majority Leader Harry Reid has promised further studies when the bill is merged with other legislation. She insisted, "We're not rushing. We are taking our time."

The partisan rift in the Environment and Public Works Committee, which delayed votes on amendments to the legislation, exposed the sharp divisions in the Senate over how to address global warming. Democrats also have been split on the issue. Sen. Max Baucus, a Democrat who said he had deep reservations about the bill, also was absent.

Hoping against hope?
Boxer had hoped to push the legislation out of her committee this week, so it could be merged with provisions from five other committees and demonstrate to the world some progress in Congress before the international climate conference begins in Copenhagen, Denmark, in December. The House of Representatives has already passed a climate bill.