If political campaign ads seem even more abundant and toxic than usual this year, it's because they probably are.

The Supreme Court opened a floodgate of ad money this year in the Citizens United decision, which eliminated federal rules not only on third-party contribution limits but on disclosure. The results have included many more ads because there is much more money to fund them, and more vicious ads because the front organizations that produce them do not have to disclose the identities of their donors.

Organizations including corporations, unions and advocacy groups may fund ads favoring particular candidates as long as they do not work directly in concert with the candidates' campaign committees.

Though much of the early concern focused on the prospect of well-heeled corporations funding campaigns, the greater issue thus far has been front groups. They collect millions in anonymous contributions and then run opposition ads that are not just negative but, often, vicious.

More than $78 million in such advertising appeared last week alone, according to the Sunlight Foundation, which tracks such spending. And the pace is accelerating as Election Day approaches.

It always has been a stretch to equate wealth - the ability to fund campaign ads - with "free" speech. It is a double disservice to the quality of political discourse to allow that wealth to be accumulated without accountability in the former of the donors' identities.

Without those identities, any message is half a message because viewers have no way of knowing the agenda, record or motives of the contributor.

Congress missed an opportunity to ensure that accountability when Senate Republicans blocked the DISCLOSE Act, which would have required identification of contributors. That made this election campaign an experiment that, so far, has produced miserable results. Congress should revisit the issue and establish disclosure requirements as a simple matter of honest accountability for political messages.