As Congress returns to work this month, the Senate will likely have another chance to vote on the DISCLOSE Act, legislation meant to mitigate the damage of Citizens United by requiring full disclosure of corporate spending in elections.

The House passed the DISCLOSE Act in June. In July, it sank in the Senate, when not a single Republican was willing to break a filibuster on the bill. Moderate Republicans Scott Brown, Susan Collins, and Olympia Snowe, despite previous support for clean election legislation, all sided with their party to kill the bill.

In the Washington Post today, E. J. Dionne writes that the support of those three senators is key to the passage of the DISCLOSE Act—though the pressure they face to oppose it is greater than ever:

As moderate Republicans, Snowe and Collins are undoubtedly looking over their right shoulders, fearful that they may go the way of Sens. Lisa Murkowski and Bob Bennett. This helps explain why they went south during negotiations over the health-care bill.

But repairing Citizens United is not an ideological question, although some cast it that way. Fiscal conservatives should be as worried as anyone about corporations using their newfound power to extract expensive special benefits from the government. Even conservatives who opposed campaign reform in the past have always insisted that they favor disclosure of campaign contributions. Disclosure is now more important than ever.

Snowe, Collins and Brown have made their careers by touting their independence. But that claim doesn’t come cheap. This is the issue on which their promissory note is due.

This election cycle has already produced plenty of examples of corporations funneling money through front groups to support or smear candidates. In an ideal world, every member of Congress would stand up to corporate lobbyists and support a bill that would throw light on that murky political strategy. But at the very least, a disclosure bill should have the active support of those who profess to be independent campaign reformers.