Dick Morris and  Eileen McGann

For the first time in memory, the two parties are holding their conventions right after one another. Within 72 hours of Obama's acceptance speech on the night of Aug. 28, in front of 75,000 adoring fans outdoors at Invesco Field, the Republican convention's opening gavel will come crashing down. How will it work? What will be the impact of these nearly simultaneous events? Nobody really knows, but the answer is critical. Usually, the post-convention polling sets a pattern that lasts at least until the candidates debate.

Will Obama's magic and aura last for the ensuing week, casting a fog over the Republican convention, obscuring its proceedings and dulling its impact? Or will the winds of criticism against Obama, for four nights in a row in Minneapolis, dissipate the vapors and nullify his bounce?

At the moment, the scheduling of the conventions appears to make a prolonged deadlock between the two campaigns the most likely result.

Normally, when conventions are held several weeks apart, the party holding the later gathering has a huge advantage. It can absorb the worst the opposition has to dish out and then work for the ensuing weeks to reduce the size of its post-convention bounce. Then, when the party with the second convention meets, it can build on an even race and structure a bounce that lasts through the fall.

That's what happened in 1996 and in 2004. Both times, the challenger party had the first convention and, in both cases, it was a good one, affording a standard 10-point bounce. In 1996, the Clinton administration nullified the bounce by signing welfare reform and other key legislation during the interval between the conventions. By the time the Democrats met in late August, Clinton had restored a seven-point lead. By the end of the convention, it was over 20 points. It didn't drop to the seven points -- Clinton's actual margin of victory -- until the China fundraising scandals of late October.

In 2004, the Republicans used the time in between the two conventions to launch their Swift Boat attack on John Kerry, offsetting the tales of Vietnam heroism that had been spun at the July Democratic convention. By the time the Republicans gathered in August, the bounce was almost entirely extinguished and Bush's bounce from his convention lasted until October.

But this year, while the Republicans got the later convention, and hence an advantage, the Democrats may have nullified the edge by scheduling their gathering right before the GOP's conclave. This juxtaposition will not give the Republicans time to clear away the Obama bounce before their convention starts.

Dick Morris and Eileen McGann

Dick Morris, a former political adviser to Sen. Trent Lott (R-Miss.) and President Bill Clinton, is the author of 2010: Take Back America. To get all of Dick Morris’s and Eileen McGann’s columns for free by email, go to www.dickmorris.com