After the lame duck session of Congress ended a few days before Christmas, watchdog groups were disappointed to learn that a bill expanding protections for government whistleblowers died in the Senate.

The bill was a product of a 12-year lobbying effort and had bipartisan support. An earlier form of it had passed the Senate unanimously, and it passed in the House after undergoing some changes. When the bill went back to the Senate for a final vote, a lone senator put an anonymous hold on the bill, effectively killing it. Tom Devine of the Government Accountability Project explains how the manuever worked:

A hold is like a passive filibuster of one. It can be removed only through the same process to defeat a filibuster: 60 votes along with days of procedural hurdles that paralyze all Senate business. While theoretically the secret senator must come out after six days, that rule is no help at session's end.

Now, WNYC’s On the Media—together with the Government Accountability Project—is trying to find out who killed the bill, and they’re calling on folks to contact their Senators to ask.

The killed bill had already had some protections removed, after some House Republicans—among them, Rep. Darrell Issa, who’d previously supported the bill—had raised concerns that the bill would help WikiLeaks and enable disclosures of classified information.

Watchdog groups had argued that such concerns were unfounded. The bill strengthened protection for federal workers who report fraud and abuse through legal channels. Without such protections, whistleblowers wary of retaliation would be more likely to go to outside organizations such as WikiLeaks, Devine told On the Media.

Devine also noted that under previous administrations, whistleblower protection legislation had been defeated on the basis that the Justice Department opposed the measure. The Obama administration, however, has stated its support for the bill, eliminating one reason traditionally given by opponents.

So the question remains: Who’s the lone senator? If you’re as curious as we are, check out the crowdsourcing effort and consider sending your Senator a quick email.