Namely: At some point in the past, preferably around 2060, the United States split up into several pieces. There's now a country consisting of Washington, Oregon, California, Alaska, and possibly Arizona, Nevada, and New Mexico; Texas is its own nation; I'm not sure what the status of the Midwest and Northeast are, but I believe both have remained part of a pared-down "United States of America" that still calls itself such. (The Pacific Coast nation is probably called "Pacifica". If it doesn't include the Southwest I think those states have also gone independant but retained VERY strong trade ties to Pacifica, have open borders with it and each other, etc.)
It was Pacifica's idea to seperate; Texas sort of jumped on the bandwagon when Pacifica had managed to make a clean break.
My question: How do you believe the government of the US would react to being presented with a 'Declaration of Independence' from a coalition of Western states, assuming a) it was at that time controlled by 'extreme right-wing' Republicans and b) thanks to the support of the UN for Pacifica as well as 'international opinion' it was obvious that reconquering the states was Not An Option?
ETA: A clarification of the situation - Whatever the US wants, Pacifica is really hoping for a quiet and amicable seperation. They'd be willing to sign treaties assuring the US of almost the same sort of access to the Pacific Ocean ports as before the seperation - assuming the US was willing to let them go without sending in the troops. Also, at least the way I'm writing it by 2060 war is unthinkable, and yes, if the US tried to invade a country that was basically handing them vows of peace, most other first-world countries - certainly the EU - would lay on the trade embargos and, if necessary, send in their own troops to support Pacifica. I think (I am not an economist, either) that with Pacifica still trading heavily, the world economy could take the hit of breaking off with the US without undue damage.
Also, by 2060 the US does not have a great number of troops anymore, thanks to attrition, an attempt to show its pe. If it wanted to nuke LA to the ground, sure, it could do that - assuming it was willing to risk retaliation. If it just wanted to *retake* Pacifica, it might not have the military strength.
I'm reluctant to use the Civil War for comparison because although there were a lot of factors there, slavery was a major one, and the tide of public opinion is going to swing the other way re civil rights in this case. Specifically, the US is considered extremely 'backwards' in terms of civil rights at the time, the Bill of Rights has basically been gutted, and Pacifica was in part driven towards seperation by a number of what they, and a lot of other countries, considered blatant human-rights abuses.
I'd look for a more recent model to inform me, but the only ones I can think of are Eritrea and Etheopia (about which I know nothing except that it happened) and the breakup of the USSR (which I don't really think is analagous ... well, maybe. Hmm.).
I don't know how this would affect matters, but Pacifica did offer citizenship to anyone from the US; the offer might have been reciprocated, I'm not sure.