President Obama’s apologists have found lots of reasons why Obama lost the debate on Wednesday, some of them pretty creative.  They range from Mitt Romney lied so much that it stunned Obama into ennui to Obama meant to do that to lull Romney into a false sense of security! Al Gore thinks it’s altitude sickness, and I agreed with him on Twitter … sort of:

I buy that Obama's debate failure was from altitude sickness … like the kind Icarus had.

— Ed Morrissey (@EdMorrissey) October 4, 2012

However, National Journal’s Ronald Brownstein probably has the best answer seen so far.  Obama lost because Obama has nothing left to offer:

President Obama didn’t have many good moments in this week’s first presidential debate. But it was telling that the few came when he was raising objections to Mitt Romney’s tax, spending, and Medicare plans. The president had much less to say about his own ideas for the next four years.

In that way, the debate spotlighted the biggest hole in Obama’s reelection effort: the paucity of specifics he has offered about his second-term agenda. To a remarkable extent for an incumbent, Obama and his team have redirected this campaign into a referendum on the challenger—a reversal of roles that Romney has facilitated with a monthlong series of gaffes and missteps. (Until Wednesday night, pretty much nothing good had happened for Romney since the minute Clint Eastwood inexplicably lugged that chair onstage on the final evening of the Republican convention.)

But the 90-minute expanse of Wednesday night’s debate proved too long a stretch for Obama to keep the focus on Romney. And when the spotlight shifted back to the president—either his record or his plans—he often seemed diffuse, if not listless. As one undecided woman in a Las Vegas focus group of “Walmart moms” put it, the president seemed “defeated, a little bit.”

Telling, indeed.  We’ve been waiting for the mythical second-term agenda for months now.  Most of us expected to see it unveiled by the Democratic convention, and some of Obama’s own advisers promised that would happen in his acceptance speech.  The omission of a second-term agenda finally got the notice of the Washington Post four weeks ago, the day after Obama’s pedestrian speech in Charlotte:

An acceptance speech is not a State of the Union laundry list of specific proposals. Its role is to set out a vision of the country’s future path. Mr. Obama was correct that he and Mr. Romney have dramatically different visions of government’s role, and that the Republican prescription of tax cuts to address any woe has left the country in terrible shape. Mr. Romney has been inexcusably vague in outlining his program, fiscal and otherwise, and he did nothing to mend this deficiency in his acceptance speech. But Mr. Obama’s speech also fell short — of his own proclaimed standards.

He vowed, “I will never turn Medicare into a voucher,” but he gave his audience no indication that his solution — controlling health care costs — might involve sacrifice on the part of seniors. He promised “responsible steps to strengthen” Social Security, which he has neglected throughout his first term. As to which steps those might be, not a word. “My plan will continue to reduce the carbon pollution that is heating our planet,” Mr. Obama said. What plan would that be? …

But the attractiveness of that vision made all the more frustrating Mr. Obama’s refusal to fill in any substance, his once again promising hard truths that he did not deliver. “They want your vote, but they don’t want you to know their plan,” he said of the Republicans. If Mr. Obama has a plan, Americans who listened Thursday don’t know how he would achieve it.

Four weeks later, Obama still has nothing to offer.  He has nothing left in the tank; he’s mailing it in.  All he can do is offer the Geithneresque approach, picking apart Romney’s plan while having nothing of his own to offer.  And if he doesn’t have anything to offer by now, Obama simply doesn’t have it at all.