WASHINGTON -- Democratic senators in the Environment and Public Works Committee faced a row of empty seats across from them this morning, as Republicans are boycotting hearings on climate change legislation.

The standoff between committee chair Barbara Boxer, D-Calif., and ranking Republican James Inhofe, R-Okla., has to do with economic projections by the Environmental Protection Agency. Republicans say that the 38-page analysis is incomplete and makes too many rosy assumptions about technological advances. Democrats say that the EPA's work was typical of what is done before the committee amendment process, and a full modeling of the economic impacts of the bill -- which would create a cap-and-trade market where the right to emit greenhouse gasses is swapped -- will be conducted before the bill hits the Senate floor.

"We've seen a pattern of partisanship which is really excessive partisanship," said Sen. Arlen Specter, D-Pa., who serves on the committee.

"We have a practice in the world's greatest deliberative body to disagree without being disagreeable. But you can't disagree with an empty chair."

Shortly thereafter, during Mr. Specter's opening statement, Sen. George Voinovich, R-Ohio, walked in -- the first and only Republican to appear.

But Mr. Voinovich was there to deliver the message that Republicans will not participate in the amendment process until the EPA conducts a full analysis.

"The time to take a detailed look at these issues is now," Mr. Voinovich said. "These are not issues that can simply be fixed on the Senate floor."

The House passed climate change legislation in June, and Ms. Boxer and Sen. John Kerry, D-Mass., introduced a similar bill in September. EPW is the first Senate committee to begin action on the bill, which likely will not advance to the Senate floor for months, if at all.

Several Democrats -- including Mr. Specter and Sen. Bob Casey, D-Pa. -- have expressed reservations about the effects of cap-and-trade on the coal industry and energy consumers. Mr. Specter, in his statement this morning, said he will be offering a number of amendments, but of the bill, "I think it's a good start."

Some Republicans have shown a willingness to cross the aisle on climate legislation -- but this early impasse could mar those chances.

Ms. Boxer has put the markup of the bill on hold for the day and invited EPA officials to take questions from anyone who wants to ask this afternoon. Mr. Voinovich said he was uninterested in querying the EPA -- he just wants the agency to get going on a comprehensive analysis.

At least two Republicans must be present for a quorum on the committee, but there is a chance Ms. Boxer could move ahead with a committee vote without Republican participation. She has not said what she plans to do tomorrow if the Republicans continue their boycott.

"If this thing is jammed through, rammed through [at the committee level, it's] going to hurt the possibility of getting the legislation passed," Mr. Voinovich said.

Washington correspondent Daniel Malloy writes the "Pittsburgh On The Potomac" blog exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.