A bill giving federal employees expanded protections against retaliation for blowing the whistle on waste, fraud and abuse died in Congress on Wednesday night, after a 12-year lobbying effort won last-minute unanimous approval for it in the House but failed to gain similar approval under special voting rules in the Senate.

A single unnamed senator put a hold on the bill, which had already passed the Senate by voice vote in a more controversial form, just before the chamber adjourned for the Christmas holiday. That decision denied the Obama administration - and many Republican supporters - a victory that accountability advocates have long sought.

The aim of the legislation was to bolster incentives for federal workers to put a halt to wrongdoing by making protected disclosures to their superiors, Congress or the public. Those who work at borders, airports and nuclear facilities, as well as law enforcement agencies such as the FBI, would be among those covered.

The Obama administration initially sought to include national security and intelligence employees and won bipartisan Senate support for doing so, but the part of the bill that covered them was stripped by supporters in recent days after House Republicans expressed concern that it might encourage disclosures comparable to the WikiLeaks publication of U.S. diplomatic cables.

Democrats countered that the bill would inhibit such breaches by specifically opening confidential, protected and legal channels for reporting classified abuse. But Michael Steel, a spokesman for House Minority Leader John A. Boehner (R-Ohio), said, "We had concerns based on the impact it could have on the intelligence community," and added that "those concerns were addressed" when the bill was altered.

The outcome left the measure's supporters fuming. "This holiday season Senate Republicans gave taxpayers a secret Scrooge. After unanimous House approval today, and unanimous Senate approval last month of a stronger bill, this evening an anonymous Senate Republican killed the reform through a secret hold," said Thomas Devine, legal director of the nonprofit Government Accountability Project.

"The senator who sabotaged this bill should come out of the closet. Good government groups want to give him the 2010 Friend of Fraud, Waste and Abuse Award," Devine said. He promised a "relentless search to find the politician who is a cowardly enemy of taxpayers."

"Protecting whistleblowers makes government better for all of us," said White House spokesman Reid Cherlin about the bill.

The bill specifically protected disclosures related to unlawful acts, regulatory violations, abuses of authority, dangers to public health and any gross mismanagement or gross waste of funds, so long as the whistleblower had substantial evidence to back a claim. It would have reversed hundreds of legal rulings that advocates say have gutted whistleblower rights, including some that barred protection for disclosures to co-workers or the person responsible for wrongdoing.

It also contained provisions specifically meant to protect against retaliation for the disclosure of any manipulation of scientific data, and, for the first time, would have allowed those who suffer alleged retaliation to request a jury trial in federal courts across the country. They now can get a hearing only before a single court in Washington that many advocates view as hostile to federal workers rights.

Rep. Chris Van Hollen (D-Conn.), a key sponsor of the bill, said, "We want to send a clear signal that whistleblowers will have the protection they deserve." Rep. Todd Russell Platts (R-Pa.), another key sponsor, said he believes the legislation will empower "those on the front lines" in the federal workforce who see wrongdoing to come forward, because it provides a legal means for them to do so. Today, he said, they are "understandably hesitant."