Over the final 18 days of the 2014 campaign, Republicans are set to outspend Democrats on ads in seven of the top 11 Senate races in the country.

In only four of those races, though, will the GOP actually put more ads on the air.

One of the less-publicized realities of the 2014 Senate campaign is that, while both parties are spending hundreds of millions of dollars of money trying to secure the majority, Democrats are getting considerably more bang for their buck. And down the stretch, they figure to have at least a slight advertising advantage in most of the key races -- despite being outspent overall.

That's according to data compiled by Echelon Insights, a Republican research and analytics firm that has launched an effort to predict future ad spending using Federal Communications Commission data. (This, we would emphasize, is an inexact science, so keep in mind that these are estimates.)

Here's the breakdown, both on total dollars being spent (on top) and on actual ads set to run (on bottom):



Echelon Insights

You'll notice in Alaska, for example, that Republicans figure to spend more than 72 percent of the ad dollars in the final few weeks. Despite that spending advantage, though, they will run less than half the ads, according to these data.

There's a similar disparity in Arkansas, though the GOP still figures to run slightly more ads than Democrats there. In fact, in only two of the races above are Republicans getting more bang for their buck than Democrats, and those two states are Michigan and Virginia, which aren't really top-tier contests.

So why the disparity between dollars spent and ads run?

1) The number of ads run isn't quite the same thing as the number of people reached by ads. You can run a bunch of ads in Grand Junction, Colo., for example, for the same price as one ad in Denver. So looking at raw numbers of ads doesn't necessarily mean Democrats will reach more people with their ads. (At the same time, it's likely both sides spend relatively similar portions of their ad dollars in big markets vs. small markets across the country, so it's still a valuable measure.)

2) Candidates get lower ad rates than outside groups, and incumbents tend to raise more money than challengers. Given Democrats have so many incumbents in the races above (nine) and Republicans have just two, that means Democrats tend to benefit more from lower rates for candidates.

3) The following tweet is from Democratic Senatorial Campaign Committee executive director Guy Cecil on Friday:

It now costs more money to buy ads in Manchester, NH than New York City. Glad we bought early! Thanks Citizens United. — Guy Cecil (@guycecil) October 17, 2014

What Cecil is referring to is the fact that reserving ads early secures lower rates. Buying ads at this point in an election can be very expensive, because the airwaves are flooded in the markets playing host to competitive races (such as Manchester).

The best strategy, then, is always to reserve the ad space early, while it's still cheap. In this area, Democrats also benefit, because they tend to reserve the space earlier. The DSCC has raised considerably more money than its GOP counterpart this cycle and, as an incumbent-protection organization, had a pretty good idea where it needed to put that money early on. And it did so.

Thus, GOP groups trying to play catch-up and even the advertising battlefield in the states that wound up being competitive have to spend considerably more on ads today than Democrats did when they reserved the space months ago.

"While Republican candidates are getting better rates than their Democratic competitors, Democrats seem to be getting much more favorable rates for issue groups and party committees," said Patrick Ruffini, a co-founder of Echelon. "Republicans are obviously much more reliant on these, which further exacerbates that ad-efficiency gap."

Republicans in the past complained that they faced sizeable advertising deficits in key states like Iowa and North Carolina, and outside groups soon came to the rescue. Similarly, on Thursday, National Republican Senatorial Committee executive director Rob Collins (Cecil's counterpart) mentioned that the race in Georgia is tightening.

That's no coincidence; if you look at the chart above, Republicans are about to get lapped on the airwaves in Georgia, and Collins -- who can't communicate directly with outside groups but can send such smoke signals -- is doing just that.

We'll see if GOP outside groups come in to close the gap. If they can afford it, of course.

A few final observations about the above chart:

Independent Greg Orman is running only 16 percent of the ads in his race with Sen. Pat Roberts (R-Kan.) down the stretch. He'll probably close the gap, but it's pretty clear he's getting vastly outspent now that the cavalry has come to Roberts's aid.

Alison Lundergan Grimes (D) faces a huge ad deficit in the Kentucky Senate race. This is because the DSCC just pulled out of Kentucky. There were some whispers that Grimes and other outside groups could pick up the slack and keep her competitive; this shows they would have plenty of ground to make up.

Republicans are getting pummeled in Michigan, Oregon and Virginia. These are no longer expected to be potential pickup opportunities, and the ad-spending imbalance certainly won't do much to change that.

And finally, the below chart is the same as above, except that it's for the past 21 days rather than the next 18.



Echelon Insights

What you'll notice is that Republicans in most races have run a higher percentage of the ads than they are scheduled to down the stretch. So the GOP's projected advertising deficit down the stretch is relatively new.

It also suggests that things change, and given GOP outside groups have come to the rescue before, they could tip the balance again.

If they want to pay the price.