I started to write a comment to Ginny’s post, but decided to stick it up here instead.
The main thing a “Tet” scenario would need is a spectacular apparent success by the insurgency, to put strong and upsetting video images in front of the American public. This does not seem to be in the cards. Even with the active support of Syria and Iran which the insurgency enjoys, their capabilities are orders of magnitude smaller than what the Vietcong and NVA possessed in 1968. The war will continue to be one of attrition on the part of the USA and its Iraqi ally, and one of media theatre and intimidation focused on the local population by the resistance. Both sides seem to have the material means to continue like this for years.
The people who sincerely want the United States to be defeated — Leftists in the USA and elsewhere, Islamic fascists in Middle East and elsewhere — have been very consistent and very focused. The Left in the USA genuinely believes that the USA is a force for evil in the world and that anyone who fights against it should be supported or at least given the benefit of the doubt. The Anti-War Movement has had decades of practice in refining their methods and message. The way Cindy Sheehan was promoted into a major figure shows the capabilities of this community and its media allies. The Left as well as the insurgency can rely on the active complicity of the news media to be a megaphone for their messages and images. Both the Left and the insurgency can count also on the complicity of opportunistic politicians, both in the USA and abroad, who see opportunities in opposing “Bush and his War”. So, the anti-War movement will stay in the game and become increasingly effective as expenses and casualties mount. This will, in turn, give the insurgency the accurate awareness that they need only persevere to have a good shot at victory.
Moreover, public support for long and expensive wars is hard to sustain in the USA under any circumstances. After three years of fighting moderate supporters bail out and want the thing wrapped up. This is a consistent historical pattern. Exacerbating this factor, our President has done a miserable job of explaining the war and rallying support for it, so support is withering faster than would otherwise be expected. Nonetheless, Mr. Bush is Commander in Chief for three more years, or so. Congress is unlikely to vote down his budget requests for the war unless public support collapses entirely — since that would mean not “supporting our troops”. See, e.g. yesterday’s vote. So, the USA has until the end of Mr. Bush’s term to get the situation stabilized and hand off the war to the Iraqis. That’s not a lot of time. Successful counter-insurgencies take more like a decade, e.g. El Salvador and Malaya.
I think that both candidates in the ’08 election will run on varying plans to remove the USA from Iraq, where fighting will be continuing due to active and passive foreign support for the resistance and the slow pace of building an Iraqi army. This is due both to American mistakes and the low quality of the underlying human material we are working with — Arab armies are generally incompetent for deep-rooted cultural reasons and Iraq is a particularly bad example of these pathologies.
It is too early to say if a viable state and army can be left behind or if we will see Saigon II and the helicopters lifting the US embassy staff out of Baghdad during the ’09-13 presidential term. I hope not, but hope is irrelevant. I won’t even give odds. Too much of what you read gives disparate and contradictory information.