WASHINGTON — Senate Democrats blocked a Republican-backed move Wednesday to scrap EPA regulations on mercury and toxic chemical emissions from coal power plants, unswayed by the contention that the rules are killing jobs, not saving lives.

The measure, sponsored by Sen. James Inhofe, R-Okla., failed, 53-46.

Picking an election-year fight over the wisdom of instituting new environmental regulations in a weak economy, Republicans argued the rules will force older power plants to close, putting people out of jobs, and will drive up the cost of electricity.

Inhofe warned senators that by voting against his measure, “you are effectively killing coal in America.”

Opponents said the regulations will improve the health of hundreds of thousands of Americans made ill by toxic chemicals spewed by coal-fired plants.

The Environmental Protection Agency estimates the rules will prevent 11,000 premature deaths a year.

When the regulations were announced last December, environmental groups praised them as a historic step more than two decades in the making.

Congress ordered the EPA to regulate the chemicals as part of the 1990 Clean Air Act, but delays and a Bush administration U-turn meant mercury and other toxins from coal plants were not controlled until the rules were announced last year.

There was little chance that the Mercury and Air Toxics Standards, or MATS, would be repealed. But the vote allowed senators to capitalize on the issue ahead of this fall’s elections.

Some Democrats from energy-producing states voted for the measure. But New England Republicans — including Mainers Olympia Snowe and Susan Collins — whose states do not use much coal and are in the path of airborne chemicals from Midwestern plants, voted against it.

Sen. Joe Manchin, D-W.Va., said the regulations will harm miners in his state, which is a major coal producer. “These people are scared to death because all they hear every day is they’re going to lose their jobs,” he said.

But Manchin’s colleague, Jay Rockefeller, D-W.Va., argued that the rules will help clean up the coal industry, giving it a viable future.

Manchin is up for re-election in November; Rockefeller is not.

Power companies have four years to meet the rules, which the EPA estimated will cost the industry almost $10 billion a year. But the agency also estimated the regulations will save between three and nine times that amount as a result of better health. The EPA also estimated that while some jobs could be lost as plants closed, others will be created installing the required equipment.

The rules require all coal plants to meet the same standards as the cleanest coal plants now operating. The EPA estimates they will cut mercury emissions by 90 percent and acid gases by 88 percent.

Power plants are responsible for 50 percent of mercury emissions in the United States. When mercury gets into water, micro-organisms turn it into a highly toxic chemical that builds up in fish.

Mercury can cause developmental problems in children who eat contaminated fish. Other chemicals emitted by coal plants are linked to cancer and respiratory illnesses.

Inhofe brought the move to strike down the EPA rule under the Congressional Review Act, which gives Congress the power to block major regulations. As it happens, Senate Democrats tried to use the same act to stop President George W. Bush’s EPA from yanking coal power off its list of regulated industries in 2005.

That bid failed, and the EPA was sued by a group of states and environmental organizations. In 2008, the U.S. Court of Appeals for the D.C. Circuit ordered the EPA to restore coal plants to the list.