The law to phase out incandescent light bulbs was promoted as a simple, almost painless, change when Congress first passed it.

By requiring that light bulbs use at least 25 percent less electricity, starting in 2012, the nation would use less energy, manufacturers would invent new, more efficient types of bulbs and the planet would be spared millions of tons of carbon emissions every year.

But the traditional light bulb — that lowly orb of glass, filament and threaded metal base — has become a powerful emotional symbol, conjuring both consumer anxiety over losing a familiar and flattering light source and political antipathy to government meddling.

On Dec. 16, the House voted to delay enforcement of the new standards until at least Oct. 1, with the Senate expected to agree, as part of a last-minute budget deal to keep the government operating through the rest of the fiscal year. Republicans have vowed to press for a full repeal of the new rules.

"This was one of those things that resonated with a lot of people, especially in the election of 2010, where so much personal liberty had been eroded," said Rep. Michael Burgess, R-Texas, a state that recently passed a law to exempt bulbs made and sold within its borders from the federal standards.

"The light bulb was what put a public face on it. People got it when you said, 'Well, why should the federal government restrict my freedom on what type of light I use?'"

Yet in some ways, despite all the heated rhetoric and political brinkmanship, the delay hardly matters.

The looming possibility of the new standards, signed into law by President George W. Bush in 2007 — and the fact that places such as Europe, Australia, Brazil and China have put similar measures in place or announced their intention to do so — has transformed the industry.

A host of new and more efficient products already line store shelves and poke out of light sockets across the country.

Many of the alternatives to incandescent bulbs are more expensive. But industry executives, government officials and environmental advocates say they often last longer and save money by reducing electric bills.

Traditional incandescent bulbs, which essentially use the same technology as Thomas Edison's original lights, waste most of their energy by converting it to heat instead of light.

That problem is largely remedied in newer technologies such as compact fluorescent lights and light-emitting diodes.