Advertising patterns demonstrate that there are really only eight states that are in doubt at this time. Barring an unexpected occurrence between now and election day, President Barack Obama is virtually a lock to win 247 electoral votes on November 6th, and Mitt Romney is a virtual lock to win 191.

With 270 electoral votes needed to win, Obama has a much easier path to victory than Romney does, and in fact could win the election if he just wins the states he is expected to win and also takes Florida. Obama has six paths to victory that involve winning half of the swing states or fewer; Romney has zero paths to victory that involve winning fewer than five of the eight swing states.

Based on where the campaigns are advertising, the eight swing states are: Florida, Ohio, North Carolina, Virginia, Colorado, Iowa, Nevada and New Hampshire.

Obama’s Paths to 270

1)     Florida

2)     Ohio plus any one of North Carolina, Virginia, Colorado, Iowa or Nevada

3)     North Carolina plus Virginia or Colorado

4)     Virginia plus Colorado and any other swing state

5)     Virginia plus any two of the following three states: Iowa, Nevada, New Hampshire

6)     Colorado plus Nevada, Iowa and New Hampshire

Immediate Conclusions

Florida can win it for Obama by itself.

Ohio needs only to be paired with one other swing state (except New Hampshire).

Either Virginia or Colorado figure into every path except the shortest one (Florida).

New Hampshire only has the potential to be relevant in three scenarios, and those are dependent on several other occurrences happening. The likelihood of New Hampshire deciding the election is fairly remote.

According to Nate Silver’s Five Thirty Eight Blog, Obama’s odds in the swing states, from best to worst, are as follows:

1)     Nevada

2)     New Hampshire

3)     Ohio

4)     Iowa

5)     Colorado

6)     Virginia

7)     Florida

8)     North Carolina

If Obama wins Nevada and Ohio, two of his three best swing states at this time, he wins the election. Therefore, his best path is to focus on Ohio and Nevada.

Either Virginia or Colorado figure into almost every scenario, so these states also should be given top-priority attention.

Iowa figures into as many scenarios as Nevada, but there is only one scenario where Obama needs Iowa if he wins Nevada. Nevada looks like a likelier win, so Nevada should be prioritized over Iowa.

Although Florida is one of the longest shots for Obama to hold, its potential to wrap the election up for Obama, even if he wins no other swing states, dictate that it should be given attention. If nothing else, tying up Romney’s resources in Florida keeps him from spending more money in the more crucial states.

New Hampshire, with only four electoral votes, is unlikely to be decisive, and Obama’s hardest lift is North Carolina. If resources have to be husbanded down the stretch, these two states should be conceded.

In short, the Obama campaign should do as follows:

1)     Focus heavily on Ohio, Nevada, Virginia and Colorado.

2)     Compete in Florida, but not to the detriment of Ohio, Nevada, Virginia and Colorado.

3)     Give as much attention to Iowa as possible without jeopardizing efforts in Ohio, Nevada, Virginia, Colorado or Florida.

4)     Give enough attention to New Hampshire to keep it competitive in the unlikely event that it is needed.

5)     Concede North Carolina. While it can be won with a great effort, it is too heavy of a lift to justify the expenditure of resources that would be necessary.

The math is much trickier for Romney, who must win at least five of the eight swing states to win the election. He cannot possibly win without taking Florida, and it will be exceptionally difficult for him to win without taking Ohio, North Carolina and Virginia. If Romney loses Ohio, he must win every other swing state. If he loses North Carolina or Virginia, he must win Florida, Ohio, Colorado, and two of the remaining three swing states (Iowa, Nevada, New Hampshire). If he loses North Carolina and Virginia, or North Carolina and Colorado, he cannot win.

Romney’s Paths To 270

1)     Florida, Ohio, North Carolina, Virginia and any other swing state

2)     Florida, Ohio, Colorado, plus North Carolina or Virginia, and any two of the remaining three swing states (Iowa, Nevada, New Hampshire)

3)     Every swing state except Ohio

Immediate Conclusions

Romney cannot win without winning Florida.

If Romney loses Ohio, he has to win all seven remaining swing states.

Losing North Carolina or Virginia would force Romney to win at least six of the remaining seven swing states, including Florida, Ohio, Virginia and Colorado. (However, he could lose Virginia and Colorado and still reach 269 by sweeping the remaining swing states; assuming Republicans maintain control of a majority of U.S. House delegations, which seems likely at this time, a 269-269 tie in the electoral college would mean the election of Romney by the House.)

In short, the Romney campaign should do as follows:

1)     Win Florida at all costs. There is no chance of victory without winning Florida.

2)     Focus heavily on Ohio, North Carolina and Virginia, as any combination not involving these three states, plus Florida, makes victory a near impossibility.

3)     Spend heavily in Colorado, which is his next-best bet.

4)     Assume Obama does not spend heavily in New Hampshire and capitalize there.

5)     Concede Nevada and focus on Iowa. Unless Romney loses Ohio, he doesn’t need both, and Iowa looks slightly better for Romney than Nevada does.

The Bottom Line

Of the eight states in doubt, there are no scenarios in which Romney can be elected without winning at least five of those states. However, Obama has a path that requires him to win only one of those eight states, two paths that require him to win only two of those states, and two more that require him to win only three of the eight swing states. Obama has six ways to win that require victories in four of the eight swing states or fewer. In short, Obama has a considerable advantage in the Electoral College and can spare his resources by focusing in on four or five of the swing states; Romney must go all-out in at least seven of those states to have a real chance to win.

Only two states are crucial to both candidates: Ohio and Virginia. Television viewers there can count on three more months of advertising saturation.