Based on the arguments this week it is certainly possible — more likely than not, I would say — that the Supreme Court will strike down the individual mandate and find that the entire statute must fall as a result. What then?

For starters, it is entirely likely that the left, which usually frowns on court-bashing (who can forget the swooning over former justice Sandra Day O’Connor on this point?), will launch an assault on the Supreme Court and its legitimacy, accusing the five “conservative” justices of “politicizing” the law. As transparent as this may be, the argument will need to explain how the five justices are political and the four (including President Obama’s former solicitor general) are pristine defenders of the law. But logic is not a barrier for those who will kick up a fuss.

The stakes here are so high that I fully expect the left to impugn the impartiality of the justices who rule against them. We’ve seen hints of this already. Politico reported on the pre-spin:

Bush and Citizens United, taken together, are both partisan, political and corrupting,” said Tom Perriello, a former Democratic congressman from Virginia who now runs the liberal Center for American Progress Action Fund. “They cast doubt on the legitimacy of the court.” . . .

Harvard law professor Michael Klarman, who has written two histories of the high court, said the fact that the fight over the health-care law is playing out according to the standard Republican vs. Democrat script — the same script as the 2000 election fight — has eroded the idea that the GOP-appointed court is rooted in restraint and precedent-based impartiality.

The left can never be accused of being unpredictable.

Aside from the left’s excuse-mongering what could we expect?

First, Mitt Romney will be forgiven if he indulges in a big “I told you so,” since he defended his health-care bill on the grounds that the federal government is limited in ways the states are not. But then he would be wise to move forward on two fronts.

First, Romney will likely argue the president spent the lion’s share of his first term on a bill that was unconstitutional. He scared employers, burdened the private sector, frittered away congressional time and energy and engaged in nasty partisanship for nothing. And, meanwhile, the economy goes limping along. Certainly, this argument will capi­tal­ize on the sense of demoralization that will certainly overtake the left if its handiwork is eradicated.

Romney, however, will also be under pressure to put forth his own, constitutionally-sound heath-care bill. He’s hinted at pieces (allowing inter-state insurance sales, changing the tax characterization of individually purchased insurance), but it will be incumbent on him to formulate a comprehensive plan. Ironically, his track record of pursuing health-care reform will give him some credibility in a general election and make him less susceptible to the claim that he isn’t interested in expanding health-care coverage.

On the Democratic side, after the anger and denunciations die down, the president will also need to come up with a health-care bill that passes constitutional muster. He ran in 2008, if you recall, on a health-care reform plan that did not include a mandate (he inveighed against Hillary Clinton for suggesting people should be forced to buy insurance), so he’d better dust that one off. As for a single-payer system, that would be the sort of thing to propose once he has “more flexibility” after the election.