Former Democratic National Committee chairman Terry McAuliffe is leading Virginia Attorney General Ken Cuccinelli (R) by a wide margin. Recent surveys show McAuliffe ahead by a margin that hovers in the high single digits — 7 points, according to Quinnipiac University and Old Dominion University; 8 points, according to a recent NBC4/NBC/Marist poll.

There are plenty of possible reasons why McAuliffe is ahead: McAuliffe has painted Cuccinelli as a radical conservative, while Cuccinelli’s messaging against the Democrat hasn’t been effective. Cuccinelli’s past positions scare off swing voters. Cuccinelli’s campaign hasn’t been error-free, to put it lightly. The gift scandal swirling around Gov. Bob McDonnell (R) is poisoning Republicans up and down the ballot. The government shutdown has allowed Democrats to paint Cuccinelli as a Ted Cruz clone.

But here’s the reason Republicans will blame for Cuccinelli’s shortcomings: He’s been massively outspent on television, still the dominant medium for conveying a campaign message.

And according to a breakdown of ad spending provided by a source watching the race closely, that’s a compelling point. In total, McAuliffe’s campaign spent more than $14 million on television ads between May 5 and Oct. 27, the data show. Cuccinelli has spent $8.5 million. And the outside groups backing both candidates skew in McAuliffe’s favor as well: Democratic groups like Next Generation, funded by California environmental activist and billionaire Tom Steyer, and Independence USA, a PAC funded by New York City Mayor Michael Bloomberg, have poured almost $8 million into the state on McAuliffe’s behalf. Outside Republican groups have added about $5.7 million in spending on Cuccinelli’s behalf.

Here’s the total spending, including the outside groups, on behalf of McAuliffe and Cuccinelli:

And here’s how much each group, including the two campaigns, have spent on television ads:

McAuliffe has outspent Cuccinelli almost two-to-one in the pricey Washington, D.C., market. McAuliffe has spent a lot more in the Roanoke market, which reaches voters in Southwest Virginia, and in the Harrisonburg, W.Va., media market, which reaches voters around the Shenandoah Mountains.

In fact, Cuccinelli has been outspent in every market in Virginia. Here’s where the two campaigns have spent their money:

To get a sense of who’s seeing these advertisements, here’s a map of Virginia broken down by television market, courtesy of the Web site

The two sides were at parity until about mid-August, when McAuliffe turned on the jets. Since Sept. 1, Cuccinelli’s campaign has only outspent McAuliffe in two seven-day stretches. And since Oct. 1, McAuliffe’s campaign has at least doubled Cuccinelli’s weekly spending.

Here’s a look at how the two sides have spent their money by week:

As Cuccinelli’s cash seemingly dwindles, the outside conservative groups aren’t stepping up to help him make up the difference. Here’s a look at weekly spending, including the outside groups:

A word of warning: The weekly numbers aren’t exact. Media buyers will occasionally purchase several weeks of television spots at the same time; the National Rifle Association’s Political Victory Fund, for example, bought $419,104 in cable and broadcast advertising that ran between Sept. 30 and Oct. 13. We divided that amount equally between the week ending Oct. 6 and the week ending Oct. 13.

But the totals tell the story of a race McAuliffe looks likely to win. Thanks to the financial advantage McAuliffe has been able to build, it’s been a pretty one-sided story.