But while the Federal Election Commission has established elaborate, though narrow, guidelines for determining whether the creation of a specific campaign advertisement violates the coordination ban, it has not focused on other kinds of activities between all PACs and candidates. Rules the commission adopted in 2003, still on the books, allow for regulation of this gray area, but they have been largely ignored.

“Most of the focus so far has been on the ads, but there may be a lot of other activity that is being coordinated between the campaigns and the super PACs that could be seen as resulting in a benefit to the campaign,” said Lawrence M. Noble, a campaign-finance lawyer at Skadden, Arps and a former general counsel for the election commission.

The regulations on coordination include a general prohibition on expenditures “made in cooperation, consultation or concert with, or at the request or suggestion” of candidates and their representatives. The commission’s records show that when devising this rule, it turned aside pleas from political groups to limit enforcement only to ads, saying such a narrow focus was not what Congress intended.

Nine years later, however, there is little evidence that the commission has followed through on this intent.

The commission, made up of three Republicans and three Democrats, has long been divided along partisan lines on how far to go in enforcing rules on coordinated expenditures, often resulting in paralysis.

Last fall, the commission was asked by American Crossroads if it could broadcast certain ads, “fully coordinated” with a candidate, who would be consulted about the script and appear in the advertisement. The group argued that it would not be improper as long as the ad ran outside of a time window established by the commission for “electioneering communications.”

The commission deadlocked and could reach no conclusion.

“The campaigns know the F.E.C. isn’t going to enforce the law, and so they’ve decided to do whatever they want,” said Fred Wertheimer, whose watchdog group, Democracy 21, has complained to the Justice Department about the lack of enforcement. “What is going on is just absurd.”