If there's one concern about the Obama presidency, it's the deficit.

And when the White House acknowledged it had underestimated things by about $2 trillion this week -- making for a $9.05 trillion gap through 2019 and $1.587 trillion this year -- critics yelled even louder.

Imagine for a second, however, if John McCain had won the election last November.

Bruce Bartlett, an economist under Reagan, says the deficit this year would be nearly as much.

WSJ via The Atlantic: If one goes through the March update (pp. 6-7) and the August update (pp. 52-53) and adds up all the changes to the January estimate, you find that the deficit increase since January consists of $46 billion in lower than expected revenues due to the economy (11.5%), $129 billion in higher spending due to technical re-estimates (32.2%), and $226 billion due to legislative changes to both spending and revenues (56.3%).

This suggests that we would have had a deficit of at least $1,361 billion this year even if McCain had won (January deficit plus lower revenues and technical changes and no legislative changes) ... assuming no stimulus and that the economy would have performed as well without it.

That's only 14% less than the deficit currently projected. some of the legislative changes are due to higher defense spending and other non-stimulus related programs.

If we assume that McCain's stimulus would have been half the size of Obama's that leaves us with an estimated deficit of $1,474 billion under McCain--only 7% less than the deficit now estimated.