There is no doubt that Obama, if he were to win, would be given great leeway in appointing the 4 liberal justices of the court. All of those currently serving would retire to accomodate Obama’s selections. Stevens is old, Ginsberg is sick, Breyer and Souter would be encouraged to step aside for very young replacements.
This will be possible because the dems will have 55+ votes in the Senate if Obama wins, and there are a minimum of 5 Rinos.
I am also concerned about the possibility, especially if Obama gets elected to a 2nd term, that Scalia and/or Kennedy would pass away or otherwise just call it quits.
As with all administrations, an Obama Administration will have two factions- the ideological and the pragmatic. Who a President Obama appoints to key advisory positions will give us definite signs.