Charles Krauthammer’s column today is called “divider in chief,” and it attacks Obama for divisive populist rhetoric that “makes a mockery of Obama’s pose as the great transcender” and “healer of divisions.”

Steve Benen points out that it’s not easy for a president to unite the country when the opposition party’s leaders have openly declared that his political destruction is their top priority, and have adopted a deliberate strategy of grinding government to a halt with unprecedented obstructionism to make it happen.

But that aside, I wanted to focus on one particular claim Krauthammer makes — one about Obama’s appeal to young voters and his criticism of the Paul Ryan budget — because it will be central to one of the most important arguments that will unfold this year:

Ethnicity, race, gender, class. One more box to check: the young. Just four years ago, they swooned in the aisles for Obama. No longer. Not when 54 percent of college graduates under 25 are unemployed or underemployed.

How to shake them from their lethargy? Fear again. Tell them, as Obama repeatedly does, that Paul Ryan’s budget would cut Pell Grants by $1,000 each, if his domestic cuts were evenly distributed. (They are not evenly distributed, making the charge a fabrication. But a great applause line.)

What a beaut! Krauthammer attacks Obama for assuming that Ryan’s proposed budget cuts are distributed evenly across the board, and concluding the budget would cut Pell Grants by $1,000. Ryan’s budget — which Mitt Romney supports in principle — doesn’t say cuts would be evenly distributed, Krauthammer argues, making Obama a liar.

But here’s the thing: The White House is assuming even distribution of those cuts because Ryan’s budget itself has not told us in any meaningful detail what it would actually cut to realize spending-reduction targets. The White House has openly admitted it is making assumptions about Ryan’s budget, in the absence of more detail that would make it easier to gauge what his vision would mean in practice.

Ryan wins conservative adulation from the likes of Krauthammer for his pose as a deficit scourge, even though he isn’t detailing the actual consequences of his proposed deficit reduction policies in any meaningful way. And anyone who even tries to game out the consequences of Ryan’s plan gets attacked for inventing them out of thin air, even though ... the info that would enable one to gauge those consequences accurately isn’t actually in Ryan’s budget. Neat trick, eh?

There’s a reason for all this: If Ryan were to spell out the consequences of his vision in any meaningful detail, it would be deeply unpopular. Similarly, any reasonable assumptions about what his vision would mean in the real world also risk making it deeply unpopular. So they must be attacked as fabrications. The GOP argument for replacing Obama will turn heavily on the claim that Republicans would do better on deficit reduction — even though they may never tell us how, precisely, they would cut spending to realize it. And conservative opinionmakers will cover for them the whole way.

This is worse than a shell game. It’s a shell game without the pea.