A watered-down version of a campaign finance disclosure bill got caught in election-year politics this week, when every single Republican senator voted to block it from coming up for debate.

The bill would have required that outside interest groups spending to influence elections identify their large donors. It would not have prevented or limited the spending, but it would have made more clear who was behind the effort to move votes, giving voters useful information about the groups’ motives when evaluating the message.

Both of Maine’s senators, who have supported campaign finance bills in the past, stuck with their party leaders this time and prevented the DISCLOSE Act from coming to the floor.

Sens. Olympia Snowe and Susan Collins criticized the bill, both for its content and the process by which it came up for consideration. They said it treated unions differently from corporations, giving what are usually Democratic donors more cover than those groups that typically give more to Republican candidates. And they objected to the way the bill was brought forward, with little opportunity for amendment.

Regardless of the substance of their criticism, however, the Maine senators’ votes are disappointing. It is difficult to see how the electoral system is better off with no disclosure requirements for these donors, even if the regulations are imperfect.

It would have been preferable if Snowe and Collins had found a way to vote in favor of as much disclosure as possible now and then tried to improve the law later. That would have been an example of the kind of moderate problem solving on which both senators have built their reputations.

It’s important to note that the votes were not on the merits of the bill, but on whether the bill should be debated at all.

Snowe ended her week by writing a letter to the Democratic and Republican leaders of the Senate, decrying what she called the “dysfunction” in what was once known as “greatest deliberative body in the world.”

Partisan votes by a minority that block debate on major issues of public concern are a prime example of the kind of dysfunction Snowe is talking about. Her participation in two filibusters on the DISCLOSE Act this week makes the timing of her complaint a little off.

Unregulated electioneering financed by anonymous donors is not good for our democracy. Neither is the Senate’s failure to address this problem in a meaningful way.