The bill has already passed narrowly through the US House of Representives, but it now won't be passed by the Senate in time for next month's Copenhagen summit.

That's the word from Senate Democratic leaders who say legislation on health care, overhauling financial markets and job creation will be considered before the Senate takes up a measure to cap emissions of carbon dioxide and other gases linked to climate change.

Democrats looking ahead to the 2010 midterm elections are concerned about a backlash from voters in industrial and heartland states dependent on coal.

Republicans are portraying Democrats' "cap and trade" proposals, as a "cap and tax" scheme.

The proposals call for capping overall US greenhouse-gas emissions and allowing companies to buy and trade permits to emit those gases.

One of the bill's sponsors, Barbara Boxer, D-Calif, says the Senate Finance Committee likely won't begin deliberations on the climate bill until January and it may not be finalized until March.

The bill passed out of the environment panel earlier this month.