The Republican-controlled chamber voted 50-46 to kill a provision by Sen. John Edwards, D-N.C., that would have delayed the Environmental Protection Agency rules from taking effect until at least Sept. 15 while they are studied by the National Academy of Sciences.
Edwards' proposal was an amendment to the $390 billion government-wide spending bill the Senate is debating.
Edwards, a declared 2004 presidential candidate, argued that the proposed rules would result in increased air pollution and health problems. The regulations are supposed to take effect in March.
"This administration has made new rules that are the biggest rollback of clean air protections in history," he said.
Edwards was opposed by Republicans who said the new regulations would help manufacturing companies become more efficient and reduce U.S. use of foreign oil. They also said the current rules have prevented companies from making some technological changes that would cut pollution.
"Companies stick with old, outdated technology" often because under the current rules it takes too long to get governmental approval for plant changes, said Sen. Christopher Bond, R-Mo.
Six Republicans — including five from Northeastern states that have filed suit to block the regulations — joined 39 Democrats and one independent in voting to delay the new rules. Five Democrats, including both from energy-producing Louisiana, joined 45 Republicans in voting to go ahead as planned.
Before Edwards' amendment was rejected, the Senate voted 51-45 for another by Sen. James Inhofe, R-Okla., that called for the academy study but let the rules take effect as scheduled.
The new rules would give companies more flexibility to modernize or expand without having to install expensive new pollution controls, even though more emissions may result. Plants with modern pollution controls would not have to upgrade the equipment for 10 years, and a new way of calculating pollution could reduce the chance that new pollution controls would be required.
The proposal is supported by manufacturing groups, but opposed by environmental organizations. It is also the subject of a lawsuit brought by nine Northeastern states, which are worried it will increase the air pollution blown in their direction from the Midwest and the Ohio Valley.
On another amendment Tuesday, the Senate voted 88-4 to provide an extra $300 million this year for home-heating aid for the poor, bringing to nearly $2 billion the amount the government would spend on the program.
Under Congress' budget accounting rules, the added home-heating spending would not boost the bill's price tag. That is because the amendment requires President Bush to spend $300 million in emergency funds that Congress provided two years ago but that he had not yet released.
Even so, the vote — on a day when snow and freezing temperatures buffeted the Capitol — highlighted a rift between the White House and many lawmakers of both parties over the heating aid. Bush proposed spending $1.4 billion for the Low-Income Home Energy Assistance Program this year, but the GOP-written bill provided $1.7 billion even before Tuesday's amendment was approved.
Democrats lined up a host of amendments to the bill, including efforts to add money for disabled students, long-term unemployed workers and food aid for sub-Saharan Africa. They also proposed withholding federal contracts from U.S. companies that have moved offshore to avoid taxes.
It was the fourth day of Senate debate on an overdue spending package for the government budget year that began Oct. 1. Majority Republicans had hoped to ship the bill to Bush so he could cite its completion during his State of the Union address next Tuesday night.
Instead, Democrats have used the bill for amendments that — though mostly defeated — have let them attempt to draw political distinctions between themselves and the GOP. Last week, Republicans voted overwhelmingly against Democratic amendments to raise the measure's price tag with extra money for schools, domestic security programs and other areas.