“WELL, OF COURSE, it’s former staff of mine. And, of course they’re people who support me. They wouldn’t be putting money into a PAC that supports me if they weren’t people who support me.”

That was former Massachusetts governor Mitt Romney in Sunday’s “Meet the Press” debate on NBC, asked about millions of dollars’ worth of ads being run on his behalf by a super PAC called “Restore Our Future.” Mr. Romney, with his casual “of course it’s former staff of mine,” offered about as succinct an illustration as we’ve seen of the flimsiness of the fiction that separates these candidate-specific super PACs from the candidates and of the danger that this development poses to a campaign finance system premised on limited contributions and full disclosure.

Presidential candidates may accept contributions of $2,500 from individuals and $5,000 from political action committees. Individual supporters long have been free to spend more — as much as they wished — as long as they did not coordinate with campaigns. But the Supreme Court ruling in Citizens United, combined with lower court decisions, has opened dangerous new horizons for independent expenditures. Corporations and labor unions, as well as wealthy individuals, are now free to spend unlimited amounts, and these contributions can be bundled by a political action committee.

Political strategists, Republicans and Democrats alike, are bulldozing through that opening, creating parallel campaign structures without the annoyance of contribution limits. Candidate-specific super PACs tend to be run by former staff of the candidate. Their money comes from the candidate’s top supporters. With anodyne names and no candidate fingerprints, the PACs can do the dirty work without the candidate having to take responsibility. Thus casino magnate Sheldon Adelson has written a $5 million check to Newt Gingrich — oops, make that “Winning Our Future,” the super PAC backing Mr. Gingrich — to run attacks in South Carolina on Mr. Romney’s record at Bain Capital.

The rationale for limits on campaign contributions is that huge contributions such as this run the risk of corruption or the appearance of corruption. The Supreme Court’s shaky rationale in Citizens United was that independent expenditures do not pose such a risk. Mr. Adelson’s check underscores the foolishness of that assessment. Would a President Gingrich consider himself indebted to Mr. Adelson? Would Americans perceive him as such? The risk of corruption in candidate-specific super PACs is as great as the size of supporters’ checkbooks.

Then there is the problem of disclosure. Eventually voters will be able to learn where the super-PAC money comes from. But the last time these groups had to report the identity of their donors and the size of their checks was six months ago. New reports will not have to be filed until the end of this month, after the first four primaries. Nor is the candidate-specific super-PAC phenomenon limited to presidential campaigns; it is spreading to congressional races. This is a dangerous development with no solution in sight.