Since the death of Paul Wellstone, no US Senator has as reliable a liberal voting record as Russ Feingold (D-WI).  On health care, for instance, Feingold has advocated for single payer, and at least on one occasion honestly admitted that a public option would serve as a Trojan horse for government-run health care.  The Poole Reports for the 110th and 109th sessions of Congress put Feingold firmly on the left wing of the chamber — although so far this year, Feingold has been one of the most centrist Democrats in the Senate.

What does that say about the prospects of cap-and-trade, one of the most cherished liberal policies on the Barack Obama agenda, when it’s too radical for Russ Feingold?

U.S. Sen. Russ Feingold is returning to Washington after what he called a “lively” round of county listening sessions during his August recess. Although the most high-profile issue has become health care reform, the Senate is under pressure to act on a number of other issues, including financial regulation and energy policy.

On the latter issue, he said the nation must do something to combat climate change, but he isn’t yet ready to commit to energy legislation with a so-called cap and trade provision for carbon emissions.

“I’m not signing onto any bill that rips off Wisconsin,” Feingold declared, arguing the bill’s mandatory caps on greenhouse gas emissions could put the coal-dependent Badger State at an economic disadvantage compared to other regions and nations.

What changed his mind?  Probably some good, old-fashioned “tea partying”:

At the same time, Feingold said he’s “troubled” by some of his constituents’ refusal to accept the principles of global warming, but agreed with some critics who have said the bill could stifle job growth in the industrial sector and increase energy prices.

“Western Wisconsin is particularly strong in being concerned about this because of their reliance on coal,” Feingold said of the bill, which has already passed the House. “There is a real possibility … that it will be unfair to Wisconsin and Wisconsin ratepayers.”

Obama has two separate but overlapping problems in the Senate for his cap-and-trade bill.  He will face the same contingent of Democrats that are skeptical about big-government solutions in health care, whose skepticism will grow for government-dictated energy production caps.  The bill will also get opposed on a regional basis with Senators from coal states.  Some of these overlap, such as Blanche Lincoln and Mark Pryor from Arkansas, Evan Bayh from Indiana, and others.

Feingold, however, shows the threat to the bill from what should presumably be a solid left wing.  No matter how much Feingold likes big government solutions, he understands that his constituents do not, especially when it means big hikes in energy costs and massive layoffs.  Feingold will not be alone in this, either.  Obama can expect opposition from Senators in Pennsylvania, Ohio, and West Virginia.  Robert Byrd already announced his opposition to it.  Even reconciliation won’t save cap-and-trade, because Obama will probably not get 51 votes for it, and certainly can’t possibly get 60.

No wonder Ann Althouse thinks Feingold looked grumpy during Obama’s speech this week.  He’s discovering that Obama’s more radical than he is, and he’s not liking it much.