DeMint threatens to derail the lame-duck session with a stunt. Gingrich backs him. Romney is now (check your watch) against the McConnell-Biden tax deal, Limbaugh is furious, and the tea-party right is going to hit the roof once the details of the backroom deal with Obama are fleshed out. I suspect DeMint is trying to sabotage both START and DADT if he cannot sabotage a highly popular tax compromise. He's either trying to wage war on McConnell or, more likely-insulate him from the tea-party explosion that's now well on its way.
Will he succeed? The Senate has passed the tax bill; the House looks highly likely to. So DeMint is merely doing double-damage to national security by trying to retain DADT, despite its negative effect on military readiness, and to scupper a key arms agreement with Russia.
And so the forces of nihilism meet the forces of realism. And which one has been strongest in the GOP these past couple of years?