* Opponents had put cost at $3,100

* Cut emissions largely through cap and trade program

* Vote could be put off until sometime next month

WASHINGTON, June 22 (Reuters) - Climate change legislation pending in Congress would cost U.S. households only about $175 annually in higher energy and consumer prices, far less than the $3,100 "burden" opponents have claimed would result, according to a Congressional Budget Office estimate.

"The net annual economywide cost of the cap and trade program in 2020 would be $22 billion, or about $175 per household," the CBO, which gives Congress nonpartisan advice about the impact of legislation under consideration, said in an analysis delivered to Congress late on Friday.

The House Energy and Commerce Committee last month approved a lengthy bill that aims to lower industry emissions of carbon dioxide and other greenhouse gases associated with global warming. It would do so largely through the cap and trade program, which would lower carbon pollution 17 percent by 2020 and 83 percent by 2050, from 2005 levels.

During a long transition period, the government would give away most of the required pollution permits. Companies that emit less than their permits allowed could sell, or trade, some of their permits to others struggling to meet environmental requirements.

Democratic leaders in the House of Representatives had hoped to debate and pass the legislation this week, but with farm-state lawmakers still holding out for more changes that they say will benefit rural areas, the vote might be put off until sometime in July.

FEAR OF HIGHER ENERGY PRICES

With the U.S. economy deep in recession, many lawmakers are nervous about voting for legislation that could raise energy prices as utilities, manufacturers and other companies move away from dirty fossil fuels like coal and toward more expensive alternatives such as wind and solar.

As recently as last month, House Republican leader John Boehner warned against legislation that he sees "saddling" consumers "with an additional $3,100 burden per family each year."

But the CBO came to a much different conclusion.

Low-income households would see an average net benefit of $40, mostly through rebates and other aid, while high-income families could see added net costs of $245 per year in 2020.

CBO said its analysis focused on the effect of the legislation in the year 2020, at which time cap and trade would have been in effect for eight years and the economy would have had time to adjust to the program.

House Republicans pointed out that the CBO estimated annual gross costs averaging $770 and as high as $1,380 for the wealthiest. A spokesman for Representative Dave Camp acknowledged that those figures do not factor in rebates, tax credits and aid to specific industries included in the legislation.

But the spokesman added that CBO did not factor in some potential ramifications, such as job losses stemming from the legislation.

Daniel Weiss and Andrew Jakabovics of the liberal Center for American Progress said of the CBO analysis: "The lowest-income households would actually gain under the bill. The second-lowest income households would face average daily costs of only 11 cents. And energy efficiency measures alone would save the average household nearly as much money as the pollution reduction programs would cost under this bill."