I've talked a lot about the crucial importance of Ohio, whose 18 electoral votes make up the bulk of the distance between both candidates and the 270 votes they need to win.
But Ohio alone isn't enough. The most likely battle lines leave Romney 22 votes shy of winning outright.
Any additional state would push Romney over the edge to win, even New Hampshire's relatively small prize of 4 votes.
That's kept the state in play, and it's still very much up in the air. Romney led by a wide margin until February of this year when Obama moved ahead. Obama has held that position except for a moment last weekend when Romney was the favorite by a point.
Now Obama leads by less than a point, and a new Rasmussen poll puts Romney up by 2 points, 50 percent to 48 percent.
New Hampshire is not important in a vacuum. But it is also the final piece of the puzzle for an Electoral College win without Ohio.
If Romney takes the South (North Carolina, Florida and Virginia) as seems likely, and Obama takes the Rust Belt (Pennsylvania, Michigan and Wisconsin) as also seems likely, then the candidate that loses Ohio can only win if they take every other swing state, a coalition of Nevada, Colorado, Iowa and New Hampshire.
If New Hampshire falls to Romney, Obama's next best chance to win without Ohio is Virginia, and that's not a battle he wants to have to stake the election on.
That scenario assumes a best-case no-Ohio no-New Hampshire map for the president. That is, if Obama loses Ohio and New Hampshire, but is able to take Nevada, Colorado and Iowa, he'll need Virginia to win.
Now, that exact scenario isn't the likeliest, but it does illustrate how important Ohio is, and how important other states become for the candidate who doesn't win there.
Suddenly, campaigns need to jump through complicated hoops and break out the calculators to find a path to 270 votes.
And in an interesting scenario, New Hampshire provides the critical votes for a tie in the Electoral College.
If Obama takes Ohio and New Hampshire, but Romney sweeps every other swing state, they tie at 269 electoral votes apiece.
In that case, things look good for Romney, since a tie is broken by the House of Representatives. However, the Vice President is actually chosen by the Senate, and there's a good chance the Democrats will still be in charge, leading to the strange but very real possibility of a Romney-Biden presidency.
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