I'm going to entertain a certain conceit in this diary; the conceit is that my perspective as a non-American (Canuck) allows me to observe American problems in a way you cannot yourselves easily see. Not that I am gifted in any unique insight, just that it is always difficult to self-diagnose our own flaws.
Here goes: The reason you are unable to prevent Bush from continuing to slice away civil and human rights is that Americans have come to complacently believe the constitution defends itself. That there is some kind of inherent force of nature that resists erring Presidents. As such, for far too long, there has been no one playing Offence in defence of the Constitution. That's my perception. Americans seem to believe it always worked out before, so it somehow will again today. Many here and elsewhere in the netroots are awake to the danger, but not yet the populace at large.
Sure, when Bush hits the field to QB a play, the regular characters quickly line up on the defence to stop his progress, but in this game as in football: You usually don't gain any yards playing defence. Then, when Bush loses possession, there is no QB for the Constitution, just a bunch of players running randomly and incoherently around getting smashed up until it's time to punt again.
Ok, enough with the football analogy (you guys play it wrong anyway - 4 downs?...pfft). Here's what I think is needed: A formal, coherent group of pro-Constitution legislators, organized as a caucus, with a public declared intent to roll back Bush's offences against the Constitution. Feingold, Leahy, Dodd and a few others have made some great noises, and sure they introduce bills to restore Habeas or whatnot, but they don't play together and they don't make the right demands of their congressional leadership and the White House.
The Constitution is not going to protect itself. It is a document crafted by humans, and humans are currently engaged in a process to destroy it. To make it an anachronism, bereft of significance. For too long, Bush et al have been fighting only institutional memory and the regular sort of structural inertia that makes any change difficult in a complex system.
Republicans have understood this. For example, where are the calls for Constitutional amendments to correct Bush's abuses? Why not have an amendment which spells out the limits of the President's Article II powers? Or one against torture? I know Bush's unitary executive ideas are daft nonsense designed only to distract the gullible into thinking this is all kosher, but this heightens the need to push back.
They pushed for amendments against gay marriage and flag burning. I doubt many of them expected to get them, but it put us on the defensive, and drives their voters to the polls. Let's make Republicans spend political capital fighting an amendment which limits Executive branch abuse. There are easily a dozen such avenues. Why not make pardons subject to a 2/3 Senate veto override vote? Or at least take away the President's power to pardon people who actually worked for him when they committed the crimes they were convicted of.
Previous to Justices Alito and Roberts taking the bench, there might have been some solace in the Supreme Court eventually slapping down this crap, but there have been too few Hamdan rulings and too many new Dredd Scotts. This is far too important to leave it to a gamble that Kennedy will do the right thing.
Like impeachment, these are fights that don't have to succeed to have been useful and worthwhile. Combined with a PR strategy to highlight the constitutional crisis underway, voters will respond negatively to legislators who resist reining in the Executive branch. What this kind of thing effectively does, is put legislators on record about where they stand on the Yoo theories of the executive. We know that Americans reject Yoo's interpretations. Put the Republicans in a position of defending an unlimited Executive. See how that goes over with voters.
And the best part is, it isn't just a good electoral strategy, it's actually the right thing to do. If it snowballs, more Democratic presidential candidates than Dodd, and maybe even some Repubicans might be forced to promise to cooperate with congress in limiting Presidential authority.
Democrats: You need to make an issue of this. Don't wait for it to show up in polling as something voters are concerned about. Alert them.