Even if the U.S. Congress is unsure just when it will get around to tackling climate change, U.S. corporations are sure legislation is coming—and are desperate to make sure they have a big say in what shape climate-change legislation eventually takes.

The U.S. Climate Action Partnership, a group of big companies and environmental groups, will present its “blueprint” for U.S. climate action on Thursday. The bottom line is that political horse-trading needed to get dozens of big companies on the same page is a precursor to the kind of compromises that will likely mark congressional debate on the matter—the more effort that’s made to make climate legislation politically palatable, the lower its environmental ambitions, and impact.

The group includes such companies as General Electric Co., Duke Energy Corp., Dow Chemical Co. and Alcoa Inc. A copy of USCAP’s blueprint reviewed by The Wall Street Journal provides some telling details. (A USCAP spokesman declined to comment.)

First, the U.S. shouldn’t wait for China or other big developing countries. Climate action “should not be contingent on simultaneous action by other countries,” USCAP says, though it later says that securing global cooperation to curb greenhouse-gas emissions should be a “priority” for the U.S.

Second, talk of a price ceiling has given way to talk of a price floor to make sure there’s an economic incentive to invest in new, cleaner energy technologies. USCAP proposes a floor price of $10 a ton of carbon to send the market a signal it needs to clean up.

But to avoid any economic shocks to the sytem, USCAP wants a “significant” portion of emissions permits given away for free to big polluters. That’s pretty similar to most climate bills that have bounced around Congress in recent years, with early giveaways giving way to auctions of the valuable emissions permits in later years.

Finally, the kind of cap-and-trade system that is politically achievable will do little to actually tackle two of the biggest challenges facing the U.S.—energy generation and transportation. That means the government will have to come up with a raft of other mandates, subsidies, and sundry other policies to speed development of things like clean coal and to make the transportation sector more environmentally-friendly.

Specifically, through at least 2025, the market price for carbon emissions will be too low to spur investment in so-called clean-coal technology, which is a lot more expensive than traditional coal. But since coal makes up half the U.S. electricity mix, clean coal needs to developed as soon as possible to start curbing greenhouse-gas emissions, USCAP says, lest the country “lock-in” dirty old generation technology.

So the government needs to step in and fund the development of at least 5 gigawatts of clean-coal demonstration plants by 2015, the group says, in addition to tightening emission standards for new power plants. The government should also directly subsidize underground storage of carbon emissions for the next 20 years, or until the country has 72 gigawatts of zero-emissions clean coal plants in operations; currently it has none, and the Bush administration pulled the plug a year ago on its biggest clean-coal demonstration plant.