For an example of the fluidity of campaign finance rules, as well as the tangled web of connections between candidates and super PACs, look no further than the digital consulting firm Targeted Victory.

So far, the firm’s hauled in $4.1 million working for Mitt Romney’s presidential campaign and American Crossroads, the super PAC launched by GOP strategist Karl Rove. Just down the hall, its neighbors in Arlington, Va., include an office housing four other companies working for Romney, American Crossroads or the pro-Romney super PAC Restore Our Future.

With the rise of super PACs, the jet-fueled political action committees that can take unlimited contributions, many campaign finance watchdogs have focused on the hundreds of millions of dollars being raised this presidential election cycle. But after the most recent campaign filings came in last week, ProPublica decided to track the other side of the equation: Where the money goes.

Our analysis found that more than $306 million has been spent so far by major super PACs and the five leading presidential candidates. In some cases, payees serve both candidates and the super PACs aligned with them, raising the specter that groups may be working together in ways that violate the rules, campaign finance experts said. We also found instances in which overseers of some political action committees directed hefty fees to their own companies, a legal form of self-dealing.

Among the top 200 payees, there were dozens of firms about which little is known. With generic names like Financial Innovations, Election Connections, Postage for Direct Mail Fundraising or Strategic Media Services, it’s sometimes unclear who runs them or exactly what they do. Many have short histories: Four of the six top-paid consulting firms for Winning Our Future, the super PAC supporting Newt Gingrich, have been launched since July.

At the same time, familiar names cropped up regularly among the top earners. Democratic strategists David Axelrod, Ronald Rosenblith and Barack Obama’s team from 2008 are back in place. On the Republican side, there were companies connected to Karl Rove, Carl Forti, David Carney and Michael Dubke.

Targeted Victory’s initial manager was Tony Feather, a close friend of Rove’s who served as the political director of the Bush-Cheney campaign in 2000. Feather also co-founded longtime GOP consulting firm DCI Direct and its sister firm, FLS Connect. Targeted Victory co-founder Michael Beach oversaw the national voter turnout program for the Republican National Committee in the 2008 election cycle.

Like some other outside spending groups, super PACs are allowed to raise and spend unlimited funds, but they are not allowed to coordinate with campaigns.

Yet the rules governing “coordination” have been narrowly interpreted and rarely enforced by regulators. As long as candidates and super PACs don’t discuss the granular ins and outs of their spending, such as the placement and length of election ads, they can discuss strategy. Candidates can even help raise money for super PACs, or even, say, ask their father or good friend to donate.

Campaign-finance experts say there’s plenty of room for activity that average people would consider “coordination” that legally doesn’t count. They also said when consultants work for both a super PAC and a candidate, regulators should question whether they are operating independently.

“Any time it’s the same individual who is providing advice and services to a campaign and a super PAC, there is the danger of coordination,” said Rick Hasen, a law professor at the University of California-Irvine who runs the Election Law blog. “I’m sure most of the individuals playing these roles are getting legal advice on what they can and cannot do. The human brain being what it is, though, I think it is very difficult to separate those roles.”

Expenditure records show that a company called TargetPoint Consulting provides “survey research” to Mitt Romney’s campaign while also doing “direct mail consulting” for Restore Our Future, the pro-Romney super PAC. In February, the founder told The New York Times that while he understood it could look “ridiculous,” his company had gone to great lengths to prevent improprieties, setting up a firewall between employees working on the different campaigns.

Even when the ties between super PACs and candidates are less direct, spending records show how their spheres overlap. For example, partners of GOP polling company Public Opinion Strategies set up NMB Research, a polling company that works for Restore Our Future. One Public Opinion partner, Neil Newhouse, serves as the chief pollster for Mitt Romney’s campaign.

American Crossroads uses four of the same consultants as Restore Our Future and three of the same consultants as Romney’s campaign. (This is hardly a shock: Carl Forti, a former political director for Romney, is political director of American Crossroads and senior strategist for Restore Our Future.) TargetPoint Consulting works for all three groups, although it’s only done $1,700 worth of work for American Crossroads.

On the Democratic side, NGP VAN, a company that sells software that helps with fundraising and FEC compliance, has done work for both the Obama campaign and two super PACs backing Obama. The Obama campaign has paid NGP VAN $130,000; the two super PACs have paid it less than $17,000.

Beyond potential coordination, the analysis done by ProPublica also showed how some who have set up super PACs are directing donors’ cash into their own pockets.

GOP strategist Nick Ryan, a former aide to Rick Santorum, for instance, started his direct-mail and telemarketing firm, Global Intermediate LLC, shortly after launching the pro-Santorum super PAC, the Red White and Blue Fund. Global Intermediate is nowthe second-biggest vendor for Red White and Blue, earning almost $1.9 million so far. While Ryan couldn’t be reached for comment, the super PAC’s spokesman, Stuart Roy, acknowledged in an email to the Los Angeles Times in February that Ryan’s participation with Global Intermediate was “no big mystery, they have done our phones and mail programs in multiple states (very effectively, I might add).”

Candidates are prohibited from using campaign funds for personal use and must pay “fair market value” if they hire companies run by relatives or other insiders, but super PACs, like regular PACs, have no such restrictions. For years, the FEC has asked Congress to expand the ban on candidates using campaign funds for personal use to PACs. So far, Congress has not acted.

“My standard sound-bite advice is ‘donor beware,’ when giving to any political action committee,” said Paul S. Ryan, of the non-partisan Campaign Legal Center.

Some insider transactions are on a smaller scale. A man named Gary Franchi Jr. runs both Revolution PAC, a super PAC known for its Ron Paul action figures, and Restore the Republic, a social networking site for Paul followers. Since last July, Revolution PAC has been paying Restore the Republic more than $1,700 a month for office rent. When asked if the office had telephones, desks and computers, Franchi replied: “Oh, yeah.”

But the office turned out to actually be a box in a Northbrook, Ill., UPS store. Franchi did not return follow-up calls for comment.