Kerry, D-Massachusetts, said he and the other senators drafting the legislation, Lindsey Graham, a Republican from South Carolina, and Joseph Lieberman, Independent from Connecticut, are on track to release their plan on April 22.

They want to propose legislation that would cap some greenhouse gas emissions by 2012 from electric power utilities, while expanding domestic oil, gas and nuclear power production.  

The trio also is adding provisions to spur new carbon dioxide-trapping technology for coal-fired power plants and incentives for nuclear power, all while still attracting the support of at least 60 senators who would be needed to pass the measure.

One of the potential obstacles: whether to expand on President Barack Obama's proposal for eventual drilling along part of the East Coast by giving coastal states more power over drilling in nearby waters.

Offshore drilling has emerged as a major flashpoint in congressional climate change negotiations as pressure builds on senators to produce an energy bill before the Senate's schedule is consumed by other proceedings, including November election campaigns.

It will be tough for the climate change negotiators to define a boundary that will please everyone — from drill-oil Democrats Mark Begich of Alaska and Mary Landrieu of Louisiana to New Jersey environmentalists Frank Lautenberg and Robert Menendez.

“Some people want to drill everywhere in the world without regard to anything,” Kerry said. “Other people don't want any drilling. And you've got everything in between. We are trying to do what we think is responsible and achievable.”

The House passed its own version of climate change legislation last year, narrowly endorsing a “cap-and-trade” plan that would put new, nationwide limits on greenhouse gas emissions and empower companies to buy and sell permits to release the substances.

But the Senate negotiators are headed in a different direction. They are scrapping the economy-wide cap-and-trade plan in favor of a sector-based approach that would not only limit emissions from electric utilities, but impose a possible new carbon fee on transportation fuels and eventual caps on emissions from manufacturers and other industrial facilities in 2016.

This means the transportation sector would see a new tax, probably after oil is refined, instead of a carbon cap, although the fee would be linked to pollution permits traded in the utility sector.

Kerry would not say whether he has succeeded yet in winning the support of any Republicans other than Graham for the bill he hopes to unveil next week.

On Wednesday, Senate Majority Leader Harry Reid, D-Nev., announced he would take over next week as stage manager in the uphill push to pass comprehensive climate and energy legislation.

His challenge will be tough. Along with the climate measure, he must juggle a packed Senate agenda that includes Wall Street reform, a Supreme Court nomination and more economic recovery plans.  Reid is also facing perhaps the toughest re-election campaign of his career this fall.

In an effort to keep the bill in Reid's hands, the sponsors – the Kerry-Graham-Lieberman team say they won't officially introduce the bill in the Senate when they unveil it to the public next week, so it won’t get referred to a committee.

Winning Republican support would be big breakthrough for Democrats and the Obama White House, especially as some Republican lawmakers have been sharply critical of climate legislation because of concerns industry would be hurt and also due to skepticism over the science behind global warming.