Romney’s chief opponent is not Obama. It’s time.

The daily push and pull of the 2012 election—who said what stupid thing, which party threw a better convention—is unfolding against a backdrop of economic catastrophe unseen in recent history. To predict the outcome, we have to somehow reconcile the broad historical trends, which do not favor President Obama, with the more immediate factors that do.

Data from the Signal's prediction model for the past 10 months tells the story of this tension starkly. When Republicans miss a step or drag their feet, the odds that Obama will win a second term rise. When economic news is front and center, those odds decline. If everything stays the same from one day to the next, the odds list toward Obama for the simple reason that challenger Mitt Romney is running out of time to make his case.

At the moment, that tug-of-war favors the president, whose postconvention poll bounce was larger than expected. That, combined with strong fundraising numbers for August, propels Obama to his highest likelihood of re-election since the Signal launched. Obama currently has a 64 percent likelihood for re-election over Romney.

There are four trends to consider when looking at this graph:

As Romney encountered stiffer-than-expected resistance in his march to the nomination, he began to appear vulnerable as a general election challenger. Economic indicators were looking up in the first quarter of 2012, fortifying Obama's position. If that trend had continued into the second quarter, this would not be a close election.

The jobs numbers, released the first Friday of every month, hit the skids in the second quarter. Obama's re-election likelihood tumbled with them. April, May and June were the three lowest job growth months this year.

From early July to the present, we see the influence of Father Time, who is unkind to challengers of either party. By definition, an election is the incumbent's to lose, and his or her opponent has a finite amount of time to successfully make the case for a change in leadership.

Last, we see that the conventions were a net boost for Obama. Romney netted a historically low poll bounce in an average convention and the unfortunate presence of Hurricane Isaac. Obama gained a modest bounce in the polls from his own convention highlighted by President Clinton's policy-oriented address.

The main uncertainty in our predictions is not in what would happen if the election were held today. It is in what will happen after the debates and after hundreds of millions (if not billions) of dollars in advertising hit the airwaves.

Follow the state-by-state and overall presidential predictions in real time with

David Rothschild has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. Follow him on Twitter @DavMicRot.