Barack Obama vs. Mitt Romney: Expectations develop for first presidential debate

Romney is a strong debater when he's not surprised, Fallows wrote, and because challengers usually profit from the first debate, Obama will need to use the platform to sell the idea that Romney would be bad for the country, unready for the job or worse overall.

"If economic trends are bad enough — or, improbably, good enough — to turn the election into a runaway, we might look back and say that the debates didn't matter," Fallows wrote. "But in what gives every sign of being a close, bitter, expensive and mostly negative contest, the way these men interact onstage could make a major difference."

Vice President Joe Biden and Republican Paul Ryan will meet for a vice presidential debate on Oct. 11, focusing on foreign and domestic policy and moderated by ABC News Chief Foreign Correspondent Martha Raddatz.