With just a week to go until the election, the airwaves are erupting with hard-hitting television ads, and in Tennessee the Democrats are charging that a spot paid for by the Republican National Committee constitutes racial fear-mongering against the Democratic Senate candidate, Harold Ford, who is African-American. The details of the ad hardly seem to matter — the curious issue here has been the reaction. Mr. Ford’s opponent, Robert Corker, has disavowed any connection to the ad, which he says was produced and financed without any input from him. The chairman of the RNC, Ken Mehlman, has also distanced himself from the ad.

So no one knows who fathered this spot. Thank Senators McCain and Feingold. Strict limits on contributions directly to candidates and on candidates’ ability to coordinate advertising messages with outside groups mean that even if Mr. Corker didn’t agree with the ad airing on his behalf, there was nothing he could have done to keep it from running. Voters don’t know whom to hold accountable.

By shunting campaign spending to so-called 527 groups and tendrils of national parties, McCain-Feingold hasn’t cleaned up American politics. The law has just made campaigns less about the actual candidates and more about a sideshow put on by competing interest groups. This is corrupting the political process by making it harder for voters to hear directly from the candidates for whom they will have the option to vote.

Negative campaigning has always existed and probably always will. That isn’t a bad thing. Too much of what gets tarred as negative advertising is merely information about relevant but embarrassing parts of candidates’ records that candidates would like to suppress but about which voters should know. The problem over the next week will not be that there are too many ads, negative or positive. The problem will be that too few of those ads will clearly speak for actual candidates.