Who Killed Cap & Trade?

Bradford Plumer asks:

Maybe none of the theories about what went wrong are correct. It’s quite possible that climate activists basically did a competent job —after all, they did get a big, complicated bill to the 20-yard-line in a legislative body that rarely passes big, complicated bills—and they just got unlucky. After all, if John McCain hadn’t thrown a tantrum and changed his mind about the merits of tackling global warming, cap-and-trade very well could have passed and those inside-the-Beltway greens would now look like geniuses. Maybe there’s such a thing as too much clever second-guessing. Sure, environmentalists will have to adapt to changing circumstances —right now, the focus is on protecting the EPA's Clean Air Act authority—but does climate activism really need to be completely renovated? Or does it just need to wait for the right moment to come along? (Granted, greens better hope that moment arrives before the planet heats up too much.)