Two bills floating around Congress now serve as the far side of the Overton window on climate policy. Both adopt the (relatively) stringent target of reducing CO2 emissions 80 percent from 1990 levels by 2050. In the House, there’s Rep. Waxman’s Safe Climate Act, and in the Senate, there’s Sen. Sanders’ (formerly Sen. Jeffords’) Global Warming Pollution Reduction Act.

It is a mark of how far the debate has shifted that the latter actually seems to be moving into the realm of the possible. Sen. Boxer became a co-sponsor shortly after the election, and today, the bill picked up some new co-sponsors: Sens. Barack Obama (D-IL), Hillary Rodham Clinton (D-NY), Joseph Biden (D-DE), Barbara Mikulski (D-MD), and Benjamin Cardin (D-MD).

Crazy! The strongest bill currently in play in the Senate now has the support of the most popular, mainstream Democrats.

You know what that means, right? Some Senator needs to get busy putting together an even stronger bill. Keep moving the window, people. Things are happening.