Campaign spending: Money can't guarantee polling points

CNBC looks at where the campaign money comes from and who's getting a return on their investment.

The campaign war chest apparently isn't what it used to be.

Politics and money
Deborah Harrison | Getty Images

Last week's abrupt cost-cutting by former Florida Gov. Jeb Bush, the clear Republican fundraising front-runner, is the latest sign that money doesn't necessarily buy support. Commanding only 8 percentage points among registered voters in the latest NBC/WSJ poll, Bush is in fifth place among a crowded GOP field. With nearly $30 million in campaign and outside spending (as of Sept. 30), that works out to paying about $3.5 million per polling point.

Compare that return on campaign spending with Donald Trump, who has reported less than $6 million in spending and drew 25 percent of the response in the NBC/WSJ poll. That works out to about $225,000 per polling point.

Here's how much the rest of the pack has raised and spent, and their polling point return on that investment.

While campaign finance reporting offers a look at where candidates are raising and spending money, the reports provide only a partial accounting of the true levels of fundraising and spending.

For one thing, contribution and spending details are self-reported by the campaigns, which means filings may be incomplete or include duplicate entries. There are no standard categories for spending purposes, for example, or a donor's occupation.

Read MoreWhat the candidates need to do on debate night

And while the campaigns may make their best efforts to comply with national election laws, the Federal Election Commission audits a campaign's accounting only "when a committee appears not to have met the threshold requirements for substantial compliance." As a result, few major candidates can expect an audit.

Still, campaign finance filings offer a rough snapshot of who is donating to each campaign and which parts of the country are offering the biggest financial support. Here's a look at where the candidates' donors live and what they do for a living. (Click on the tabs to view each breakdown.)

Campaign spending data are also incomplete thanks to the rise of political action committees, which are responsible for so-called outside spending — money raised and spent by organizations not officially affiliated with the candidate's campaign committee. While some outside organization identity as being for or against a specific candidate or party, others do not. (Our analysis includes "outside" spending based on the analysis of the Sunlight Foundation, an independent group that tracks campaign spending.)

So far much of the campaign spending appears to be devoted to office expenses, technology and equipment, and staff expenses as the campaigns ramp up for the early primaries; relatively little is being spent on advertising. That will likely change as the primary schedule picks up and the field thins.

Here's a look at where the candidate have spent their war chests and what they've used the money for (Click on the tabs to view each breakdown.) :

Watch CNBC's "Your Money, Your Vote: The Republican Presidential Debate" tonight. The debate will feature two sets of candidates discussing critical issues facing America today, including job growth, taxes and the health of our economy. Coverage begins at 5 p.m. ET.