*Obama wins North Carolina (15), Virginia (13) and New Hampshire (4); Romney wins the others.
Ohio is considered by many observers to be a "must win" State for Romney, without which it is nearly impossible for him to win the presidency. In the above five scenarios, in only one of the five them can Romney tie Obama if Obama wins Ohio. All the The other scenarios depend on Romney winning Ohio.
In 2004, the margin of victory for George W. Bush in the Electoral College was only one State: Ohio. And George W. Bush won by less than 100,000 votes there, even though he won the national popular vote by a much bigger margin.