Jonathan S. Tobin ponders for Commentary‘s “Contentions” blog readers whether President Obama would respond to an unfavorable ObamaCare ruling from the U.S. Supreme Court by attempting to “blow up the system,” as commentator Juan Williams recently suggested.

Some Democrats, sensing a political windfall, can’t wait to start the offensive. But while an attack on the conservative majority on the High Court would be very popular with the liberal base of his party, it’s far from clear it would help him with independents or moderate Democrats. The comparison with FDR’s court spat should serve as a warning to the White House of the pitfalls of running against the separation of powers.

Roosevelt thought he was on solid ground when he sought to change the political balance of the Court because some of the New Deal legislation that it had overturned was popular. But his Court-packing plan was defeated because even members of his own party believed he was overreaching and seeking to grab even more power for an executive branch that increased its influence on his watch.

But if FDR’s anti-Court offensive failed in spite of the popularity of the New Deal, how can Obama possibly hope to succeed when what he would be protesting would be the demise of legislation that most Americans oppose? If, as conservatives hope and liberals fear, the Court decides that the Constitution’s Commerce Clause cannot be interpreted to allow government to create commerce in order to regulate it and thereby compel citizens to make purchases, then it will be doing what the majority wants them to do.

There’s no doubt the president will seek to demagogue the issue if the health care law is invalid and try to portray the Court and the bill’s Republican opponents as seeking to snatch medicine out of the mouths of sick people, babies and the elderly. That’s a tactic that has had some success when it comes to defending entitlements against reform efforts. But a re-election campaign focused on defending the vast expansion of federal power and the budget that ObamaCare would mandate would be an invitation to a rerun of the 2010 midterms that ended in Democratic defeat.