The first presidential debate ended less than 18 hours ago but the conventional wisdom has already started to cement: Mitt Romney won and Barack Obama lost.

The question going forward in the race is "so what"? As in, how much has really changed in the race due to Romney's strong debate performance and Obama's at-times mystifying approach in the debate. Our attempt to answer that question is below.

What will change

* Romney-mentum: Going into the first debate, the prevailing storyline in the race was that Romney was holding on for dear life amid polling that suggested he had fallen behind and increasing questions from within his own party about whether he could win. Those questions were erased by Romney's powerhouse performance. And, if the Bureau of Labor Statistics September jobs report due out Friday morning shows the economy continuing its struggles, the balance of power in the race will shift even more clearly to Romney -- at least until the next debate on Oct. 16.

* Obama on defense: President Obama -- and his campaign -- have played offense in this race since the spring when they began advertising in earnest in swing states.  And, from the Democratic National Convention until Wednesday night, the Obama team was firmly parked on Mitt Romney's side of the field.  That will change now. Democrats, traditionally, have a much higher tendency than Republicans to eat their own in times of political crisis or hardship. Will they do so now? Or will they rally behind Obama and avoid the sort of "what is he doing"/"he could lose" stories that will take a bad debate performance and turn it into a bad week or a bad month?

* National polls:  Romney was already experiencing something of a bounce-back from the poll doldrums of last week before the debate but that movement should speed up a bit now. National polls tend to track the national storyline -- who's up/who's down -- more than swing state polls since battleground state voters are not only being subjected to media coverage of the race but are also being deluged by TV ads from the two campaigns.  An improvement in national polling could have a trickle-down effect on swing state polling -- remember that undecideds like to be with the guy who they think will win -- but it's far from a certainty.

* Debate expectations: Large majorities of people told pollsters before the first debate that they expected President Obama to win. Now that the first debate is behind us and Romney soared while Obama stumbled, the expectations game will flip flop. Going into the second debate in 12 days time, the central question for Romney will be whether he can keep up the high standard he set for himself on Wednesday. For Obama, it will be whether he can bounce back from a poor showing. We're not sure which candidate you'd rather be in that expectation game but it seems like that will be the framework for the Oct. 16 set-to.

What won't change

* Obama's electoral college edge: Even if you posit that Romney's performance might move Ohio back in his direction, he still faces a very narrow path to the 270 electoral votes he needs to win the election.

Here's our current electoral map:

Even if you take Ohio from Obama, he is still at 237 electoral votes. And even if you give it to Romney, he's still only at 224. As we have written many times, Republicans -- including but not exclusive to Romney -- have a far lower electoral vote ceiling than Democrats at this point. And, while Romney may well get a bump in polling in swing states, it doesn't change the fact that Obama retains an electoral college edge.

* Partisan polarization: It's hard to imagine Wednesday's debate changing anyone's mind except for -- maybe -- that thin sliver of undecided voters who almost certainly can/will change their minds again between now and election day.  Is there some segment of the Democratic base who got less enthusiastic about President Obama last night? Absolutely. And is there a portion of the Republican base who feel far more excited about Romney today than they did yesterday? Yup. But, neither party base (or even people who lean strongly one way or the other) is going to move off of their candidate because of a single debate. Nothing, literally, has created any major movement in this race; why would a debate -- albeit it one as one-sided as last night's?