We’ve spent a lot of time on this blog in recent weeks detailing the fact that a handful of wealthy donors have changed the presidential election game by sending millions of dollars to GOP-leaning super PACs and outside groups.

Those commercials have helped Mitt Romney even the score in the 2012 ad game.

But while the rich are certainly keeping Romney in the game early in the presidential race, he will rely on plenty of less-well-off voters if he is to win the presidential race this year.

Case in point: the chart below, which is based on data from Sentier Research and shows various measures of income in three sets of states — red states, blue states and swing states.

As you can see, the less wealthy a state’s voters are, the more likely the state is to be Republican. In total, eight of the 10 states with the highest average income are blue states, while the 10 states with the lowest income are all red states.

Here's another way of looking at it:

Part of this, of course, is because blue states tend to be more urban and have affluent population centers in the Northeast and on the West Coast, while red states tend to be more Southern and rural. There just isn’t as much money in more rural areas of the country, but the cost of living is also much cheaper than it is in the city.

Exit polling in recent elections has shown wealthy voters do tend to vote more Republican (though those making more than $200,000 went for Obama in 2008), while lower-income people vote more Democratic.

But in 2000 and 2004, when the GOP won a pair of tight presidential races, they were able to snag 44 percent of voters in households pulling in less than $50,000 per year. That number dropped to 38 percent in 2008, when they lost, but rose to 43 percent in 2010, when the GOP made huge gains nationally.

The reason the lower-income vote is so key is that it’s such a large portion of the population — 33 percent. The wealthiest of voters, on the other hand, comprise a sliver of the overall electorate.

Those wealthy voters are great for Republicans when it comes to funding super PACs, but winning elections requires wooing many middle- and lower-middle-class voters.

That’s why we’ve seen so much “fair share” talk from Team Obama. Time will tell about whether it worked.