Stephen, the worry is pretty basic. It amounts to saying Reid’s decision to abandon cap-and-trade is a tactical retreat. That this is the corner he’s has been backed into, and he’ll make another run at it if he can.

A lame-duck session gives him one opportunity to do that, especially if he can sneak cap-and-trade into a conference report. Letting the executive cap carbon with a big assist from the Courts is, as you say, another means to the same end. But the legislative route is no doubt the preferable one, since the EPA route leaves carbon regulation at the whim of the president (who won’t always be Barack Obama) and his enforcement priorities, and would be subject to abrogation by a Republican Congress.

The advantage of the lame duck session is, obviously, that electoral pressures are non-existent for lame ducks, and minimal for the newly elected. The conference report is filibusterable, yes, but conference committees are relatively obscure, closed-door affairs (the occasional Barney Frank dog-and-pony show notwithstanding) and don’t get the coverage outside the hardcore political press that floor votes do. This added layer of opacity between constituent and representative isn’t quite at the level of positively byzantine “deem-and-pass” or “budget-enforcement” resolutions, it might be enough to do the trick.

Here’s John Fund riffing on Mike Allen to that end:

Mike Allen of Politico.com reports one reason President Obama failed to mention climate change legislation during his recent, Oval Office speech on the Gulf oil spill was that he wants to pass a modest energy bill this summer, then add carbon taxes or regulations in a conference committee with the House, most likely during a lame-duck session. The result would be a climate bill vastly more ambitious, and costly for American consumers and taxpayers, than moderate “Blue Dogs” in the House would support on the campaign trail. “We have a lot of wiggle room in conference,” a House Democratic aide told the trade publication Environment & Energy Daily last month.

Indeed, Fund suggests it might not just be cap and trade, but deficit commission-recommended tax hikes and even card check, that make their way into a lame duck session. This would make forces in play in the House, and not just the Senate, salient. Take the “Blue Dogs” who, as we know, usually cave under pressure from leadership — and imagine the pressure that could be brought to bear by a Nancy Pelosi three weeks from losing her gavel.