Obama and the deficit

It was recently reported that the US budget deficit has now hit $1.5 trillion, or in more ominous language, 9.8% of GDP.
We're talking about some serious debt here, so bad in fact that it's getting close to the tipping point of being unmanageable. So what is Obama to do? He's recently caved in on the high income tax cuts (with the obvious plan of opposing then when they expire in an election year), and the Republican vultures are now circling around "Obamacare", and to a lesser extent Medicare. Republican House Leader John Boehner joined in the ridiculing of Obama with the jibe that "America's Sputnik moment is the fact that we're broke, and the American people know we're broke and we've got to do something about our spending''.
Well Boehner is dead right about that, and any responsible government would start looking at what's massively bloated and in need of a trim? The obvious logical answer is the Defense budget, which is around 5% of GDP. But this of course is the untouchable sacred cow of US politics, not even the Democrats want to touch this one and be accused of being "soft". But sooner or later the US will realise that it has no other option than to abandon its overseas follies. But as they say, pride comes before the fall, and the only real danger here in the years ahead is just how far are the political establishment going to allow the US to tumble before they face the inevitable? My instinct tells me they have a Saddam Husseinesque pigheadedness to these things, and they will fall embarrassingly low before admitting the reality?