Despite widespread public opposition to the Supreme Court’s Citizens United decision and multiple exhortations by the president for Congress to act, Senate Democrats were unable to overcome a Republican filibuster to pass the DISCLOSE Act, a bill requiring interest groups to name the donors behind their campaign ads, in the months leading up the midterm elections. Next year, when the GOP claims a majority in the House, the odds of passage are slim. “Um, no,” said presumptive House Speaker John Boehner’s spokesman when asked if Republicans might introduce a version of the DISCLOSE Act next year.

The last chance, then, for Congress to put some form of disclosure legislation on the books before the shadowy spending process repeats itself, in grander fashion, in 2012 might be now, the lame-duck session in advance of the swearing-in of the much more Republican 112th Congress in January.

But if the numerical chances of the bill’s passage in the Senate — it will only need the votes of two Republican senators to overcome a filibuster when Congress returns from its campaigning break next week — will never look better, the level of trust and communication between key Democratic and Republican Senate offices typically engaged on the issue of campaign finance stands at a seeming all-time low.

Democrats in leadership are now weighing the idea of stripping the less essential provisions of the DISCLOSE Act — measures to prohibit spending from companies holding government contracts or those exceeding a certain threshold of foreign ownership — as an act of good faith in order the counter Republican qualms about the bill and make one last-ditch effort to pass it. They’ll only do so, however, if they anticipate success, and the current breakdown in negotiations between the key parties is making them wary about the bill’s chances of garnering any GOP support at all.

How has a year’s worth of legislative effort on a popular measure now found itself on the brink of failure, and what might make it still succeed? An understanding of the bill’s chances in the lame-duck session requires a look back at its struggles through Congress and the reasons for the current standstill.

The DISCLOSE Act’s problems began with its personnel. The bill originated in the offices of Sen. Chuck Schumer (D-N.Y.) and Rep. Chris Van Hollen (D-Md.), legislators best known for their efforts, as chairmen of the Democratic Senatorial Campaign Committee and Democratic Congressional Campaign Committee, respectively, to get their fellow Democrats elected. Consequently, it was viewed with suspicion by House Republicans.

“When you immediately go to the two lawmakers who are responsible for getting Democrats elected and say, ‘Please write us the bill,’ a lot of Republicans looked at that and said, ‘Huh, that’s a curious choice,’” said Sean Parnell, president of the Center for Competitive Politics, which advocates against imposing limits on campaign spending. “It was the chair of the DCCC and former chair of DSCC leading the process. There was no way that was not going to be seen as partisan. From there it just kind of all went downhill.”

With the Senate calendar and key staffers still tied up with health care reform and financial regulation, it fell to the House to get the ball rolling — but House Democrats said the bill’s basic idea never gained traction among Republicans.

“We released a framework to the public four months in advance of introducing the bill and we reached out to specific Republicans who normally engage in campaign finance issues,” said a Democratic aide who worked on the bill. “We never were approached by Republicans to say they’d vote for stripped-down disclosure provisions.”

Only two Republicans — Reps. Ahn Cao (La.) and Mike Castle (Del.) — signaled support for the bill, so House Democrats proceeded to make it something of a wish list. They added provisions barring companies with federal contracts or those exceeding a certain threshold of foreign ownership from spending independently to influence elections. And they also made an exception for longstanding nonprofits — like the Sierra Club or the National Rifle Association — that met certain membership requirements.

The result was a bill that arrived fully formed in the Senate at the end of June, but one that also provided ample opportunity to its opponents (or would-be supporters) to hammer it as partisan or unfair. The provisions barring certain companies from spending looked to some like built-in advantages for unions, while the NRA carve-out, as it became known, provided an ironic special-interest twist on a bill meant to be about good government.

When the bill came up for its first Senate vote in July, however, Democrats hoped they could still pressure Republicans with a reputation for past leadership on campaign finance issues — like Maine Sens. Olympia Snowe and Susan Collins — or newly elected Sen. Scott Brown to cast a vote in favor of the overarching concept of disclosure. But these senators objected to the lack of a committee mark-up or other opportunities to make constructive changes to the bill.

“Unfortunately, the Senate Majority Leader chose to bring forward a bill that doesn’t live up to its title,” Collins wrote in a statement after her first procedural vote against the DISCLOSE Act. “It was drafted by Democrats behind closed doors. No committee hearings were ever held on this legislation; therefore, there never was an opportunity to make any changes to this bill or mark-up in the committee process before we were asked to consider it.”

Democratic aides in the Senate, however, insist they gave Republican senators like Snowe, Collins and Brown every opportunity for input into the bill.

“When I say we offered them a seat at the table it was, literally, ‘Come write the bill with us. Here’s a list of principles and tell us how you’d like to write it,’” said a Democratic staffer who worked on the bill in the Senate. “It could not have been a more welcoming process, but there was very little input offered.” After initial signs of engagement on the issue, Republican offices stopped responding to emails from Democratic staffers. (The offices of Sens. Snowe and Collins also did not respond to repeated requests for comment for this story.)

But by allowing a vote on the same bill that had passed the House and not anticipating the attacks that would be leveled against it, Senate Democrats failed to move the bill and, worse, lost the battle of public perception over whether the bill was a push for transparency or a thinly veiled attempt to sway the outcome of the pending midterm contests in their favor.

By the time the bill was slated to be brought up again in Congress for a vote in late September, it suffered from a breakdown in trust. Both sides realized that the current bill was a nonstarter, but there was no time in the packed legislative schedule to take the multiple days required to introduce a new, stripped-down version. Instead, Democrats urged Snowe and Collins to vote for cloture on the bill as it stood, on the assurance that the Democratic leadership would scrap whatever the senators didn’t like when it came time for debate and amendments. But such a deal would have required the confidence of all parties.

“My understanding — and I’ve talked to both Republican and Democratic offices — is that Democrats were saying, ‘Well, just tell us what you want,’ and Republicans were saying, ‘Tell us how you’ll change it and then we’ll talk,’” said Meredith McGehee, who lobbies for greater transparency in campaign finance for the Campaign Legal Center.

Other campaign finance reform advocates take a more cynical view. “A pared-down version was being discussed in the last round and that wasn’t what the issue was,” said Craig Holman, a campaign finance expert at Public Citizen, a citizen lobby group. “The Republicans, down to Collins and Snowe, even though their public denunciations were about unions, none of them ever meant that. All they wanted was anonymous corporate support in 2010 and 2012.”

In either case, the Maine senators, having already decried the bill once, cited their same complaints and voted ‘no’ once again. A vote for cloture was too close to a vote for the bill itself, and moreover, it opened the door to the possibility of Democrats pulling a fast one and passing the bill without amendments, denying them any input and earning them the wrath of the Republican caucus for enabling Democrats to enact their agenda. The bill failed to overcome a filibuster by a single vote.

Now, facing a lame-duck session with a host of pressing items on the agenda — from the START Treaty to an unemployment extension to the expiration of the Bush tax cuts — Senate Democratic leaders are skeptical that a disclose-only bill can earn Republican support. On the one hand, it would address the bulk of Republicans’ complaints about the current bill, but on the other hand, trust is so frayed that neither side is able to receive assurances as to the other’s thinking on the issue.

The impending seating of a new Republican senator later this month, special election winner Mark Kirk of Illinois, has added a new element of suspense to the mix. While his arrival raises the bar of Republican support required to proceed with debate, some campaign finance experts see in Kirk the kind of moderate voice who spoke in favor of better disclosure laws on the campaign trail and could champion a stripped-down bill as a triumph of good, clean government over the larded Democratic bill. But others doubt that casting a vote against the wishes of Senate Minority Leader Mitch McConnell (R-Ky.) — who has made a personal mission out of rolling back campaign finance laws — is high on the to-do list of the incoming freshman senator. (Requests for comment from Kirk’s office were not returned by the time of publication.)

Even if the bill is unlikely to pass, argue some advocates, at least Democrats could finally get Republicans to go on the record definitively on the issue of disclosure.

“Bring up a bill with just the disclosure provisions and take away a number of arguments that we feel are not correct but others have used to make excuses about not voting for it,” said Fred Wertheimer, president of the campaign finance reform group Democracy 21.

Whether the benefits of a symbolic vote on disclosure outweigh the importance of floor time that could be spent on other issues, however, remains an open question. Senate Majority Leader Harry Reid’s (D-Nev.) office said that Reid will defer to Schumer on the content of the bill and that the Democratic leadership has not yet reached any decisions on what it will push in the lame-duck session.

But Holman, speaking on the eve of the election, was less hopeful. “If the results are a fairly sweeping Republican victory,” he said, “then I would fully expect the lame-duck Congress to honor the tradition of doing lame-duck work.”