Parliamentary life in this country is backwards from Europe. In Europe you fight the election, then form the coalition. Here you form the coalition, then fight the election.
And all coalitions can be split. Any coalition large enough to govern will ipso facto have at least one fault line along which it will split. The bigger the coalition, the more fault lines.
The traditional division of the President's roles into Head of State, Chief Executive, and Party Leader doesn't take into consideration that the first two are -- not in an Addinton/Yoo way -- unitary in a way that the third is not. The president's third role is Coalition Chief.
At any given time we have in the US four or five parties, but only two labels. American politics is coalition politics.
The Democratic Senate ‘majority’ is not a majority. It’s a healthy plurality of about 40 votes. A similar math can be found in the House. Beyond that core, the coalition-parner 'Democrats' begin.
Being able to fracture a ruling coalition won’t produce legislation, but it can stop or effective neuter legislation quite easily. The Rove-era GOP's 50%+1 theory of governance was an attempt to avoid the perils of coalition government.
The fissiparous nature of coalitions is why the domestic-policy landscape is littered with half-measures -- a history of failures, if you will.
A generation ago, you had an informal alliance between the remains of the Southern Democrats and the GOP, over the war in Vietnam and civil rights, that kept a paper Democratic majority from doing all it wanted to, or could have on social issues, though the votes were technically there. Medicare, however successful it is today, and popular it is today, even with Johnson’s legendary parliamentary skill, and Congressional majorities, is precisely the sort of half-a-loaf program that the single-payer-or-bust forces decry.
A generation before that, in the depths of the Depression, FDR, though armed with huge Democratic majorities and political wizardry whose equal has not since been seen, got Social Security passed in ‘36-37 by the expedient of making it whites-only —- the only way to shepherd it across the fault lines in the Democratic coalition of those days. Another half-a-loaf program. (It wasn't until '55 that domestics and most agricultural workers, i.e. people of color, got into SS.)
A generation before that, TR's progressive wing of the Republican party was able to fracture the Democratic coalition by peeling off enough populists to cripple Bryan -- who ran on all three party ines in some states in '96 -- in his run against Taft in '08.
In six months, Obama -- who's good, but not LBJ good, not FDR good, not Bryan good -- won’t be able to do anything.
Sometimes it will be the obvious Blue Dogs who are peeled off the coalition, but not always.
Sometimes a righto-leftist Congressional bloc, unable to agree on what to do, will be able to agree on what to stop. We saw the bloc begin to emerge on the supplemental budget vote. You saw it start to emerge on ACES, where undoubted Democratic progressives Kucinich and DeFazio voted with Minority Leader Boehner. ACES passed by one (1) vote. I expect health care reform to fall victim to this dynamic.
Even if some HCR bill is produced, the next big ‘Democratic’ bill after that — immigration? — will not pass at all, thanks to either Democrats on the right, or Democrats on the left, plus the Republicans.
What’s the downside for a noncooperative Democrat? Obama can’t call for new elections, as Gordon Brown can, and if he could, Congress is assured of a 95% incumbency return rate whatever happens at the other end of Pennsylvania Avenue. Yeah, it’s more fun to be in the majority, but of the 256 Democratic reps, even in a 2010 blowout, 225 of them aren’t losing their jobs.
The parliamentary power of the President -- any president, Obama included -- is greatly exaggerated.