All Republicans except one are boycotting the start of committee debate on a bill to curb greenhouse gases in a protest that the bill's economic costs have not been fully examined.

Republican Sen. George Voinovich of Ohio attended the session to explain the GOP's argument for staying away. He said the tactic "is not a ruse" to block the bill, but concern that is widespread impact on the country has not been made clear.

Sen. Barbara Boxer of California, the panel's chairman, argued the EPA 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."