Democrats and Republicans on the Senate Environment and Public Works panel tried Tuesday morning to overcome a partisan standoff that could derail a major climate bill even before the committee votes.

But despite tentative overtures by each side, the feud appears to be continuing.

Committee Republicans followed through on a threat to boycott Tuesday morning’s session, saying they won’t begin work on the bill until they see a full cost analysis of the measure, which would cap greenhouse gas emissions and establish a market for trading government-issued pollution allowances.

Chairwoman Barbara Boxer , D-Calif., appears ready to carry through on a threat to break with normal procedures and move the bill through committee without them – a move the panel’s ranking Republican, Oklahoma Sen. James Inhofe, called a “nuclear option.”

One Republican, George V. Voinovich of Ohio, did appear at the committee meeting, offering a lengthy plea to Boxer to delay the markup until the EPA completes a complete cost analysis that it says would take about five weeks. “This is not a stalling tactic,” he said. “It is not a ruse to delay marking up a climate bill. This is an attempt to get the best information about a bill that will affect the entire country.”

But Boxer and other committee Democrats were unmoved, arguing they have already provided more than enough analysis of the legislation. The EPA, Congressional Budget Office and Energy Information Administration have all produced lengthy cost analyses of the House-passed climate bill, which Boxer called “90 percent the same” as the Senate bill.

Sheldon Whitehouse , D-R.I., said, “we are very close to a completely accurate estimate. People might say, ‘Why not wait?’ Because as soon as you amend it, you change it again. What are they going to do, wait five weeks to analyze each amendment?”

Boxer told the committee that Senate Majority Leader Harry Reid , D-Nev., has promised a full, detailed cost analysis of the final climate change bill that he will assemble from versions approved by the Environment committee and other Senate panels.