Over the next few days, post-debate polls could show Romney taking a narrow lead in states like Virginia, Colorado, or Florida. But to know whether Romney has upset the president’s Electoral College advantage, follow the polls in Ohio, Wisconsin, Nevada, and Iowa. If Obama retains his lead in Wisconsin and Ohio, then Romney needs to win both Nevada and Iowa to win the presidency. If Romney can fight back in Ohio, then Obama leads in Nevada and Iowa would allow him to prevail with any additional state, like Ohio, Colorado, or Virginia, where the polls will probably still show an extremely tight race. But if Obama retains a clear edge in Ohio, Nevada, and Iowa, then the Romney campaign still has much more work to do.