A quick glance at the polls suggests the first presidential debatehas had a huge impact, at least it has in the short term. Romney is ahead or tied in every post-debate national poll and leads in a number of swing-state polls. The polls are, I repeat, a snapshot in time, but you can’t argue that the debate didn’t matter. A lot.

Liberals say the problem now with President Obama’s campaign is a lousy debate. Conservatives say the problem is a lousy four years. Who is right?

Let’s mull over an alternate history of the Obama administration. Beginning with the stimulus, let’s say Obama seizes control of the agenda from Congress. He dispenses with non-stimulative wish-list items and includes a number of Republican ideas, including shovel-ready defense jobs. When the omnibus spending bill comes along full of earmarks, he vetoes it. He doesn’t wait to set up a debt commission. It is selected and completes its work in 2009 (not 2010). Obama embraces Simpson-Bowles and gets its debt plan, including tax reform, through Congress over the objections of hard-liners on both sides.

As a result, no tea party movement comes into being, there is no credit downgrade and the Democrats hold the House in 2010. Obama then works on health-care reform for the non-poor and non-seniors, coming up with a deal to which some, but certainly not a majority of, Republicans sign onto. He takes the Bush comprehensive immigration plan from 2007 and gets that passed as well.

Now, imagine what the debate would be like. What would Mitt Romney (if he were still the nominee in our parallel universe) have to complain about?

You see, you can have a great first term and still screw up a debate. It happens. But it is very hard to have a first term like Obama’s and win a debate against an able opponent. Fixing Obama’s posture or giving him more zingers might help, but that won’t give voters a reason to vote for him.

Obama’s set of policy choices and failures determined the campaign he had to run (excessively negative, disqualifying Romney) and set up the worst debate performance in memory. Given the choice between snappy retorts and the parallel history of the last four years, which would Democrats prefer? I thought so.