President Obama faces an enormously difficult challenge over the next few weeks.

On the one hand, this moment is ripe for fundamental change. There is a pervasive sense that the nation is at a Sputnik moment when it either rises to face the international competition or it does not. Commissions are churning out sweeping proposals. The economy is strong enough for policy makers to think beyond the immediate crisis but not so strong that it allays the national fear of decline.

On the other hand, just as the popular longing for change is at its strongest, the political barriers preventing change are at their strongest, too. The Democrats in Congress distrust the White House and can barely work with the Republicans. Republicans are not in a mood to compromise and can barely work with the Democrats. Many in both parties are willing to wait until 2013, when their side might have more leverage. Voters are cynical about all of them and want every program cut except the ones they benefit from.

Obama’s challenge in the State of the Union address is to give voice to the inchoate longing for change, and to chart a political path through the Washington minefield so that voters and bond markets have the sense that the country is at least beginning to grapple with its problems.

To do that, the president doesn’t have to go out on a limb and embrace specific (and politically suicidal) hard choices. But he probably does have to violate some taboos, on right and left, to give people a sense that everything is now up for discussion.