In his best-selling book A National Party No More, maverick Democratic Sen. Zell Miller (Ga.) describes his evolution from a loyal Southern Democrat to a renegade one. As with most political conversions, Miller's involved an event that he describes as "the straw that broke this old camel's back." That straw was the decision of Senate Democrats before the 2002 elections to insist that the new Department of Homeland Security extend all sorts of union-backed rules and protections to its employees, even when these rules clashed directly with America's security needs.

As the debate unfolded, Miller found himself in full agreement with the mainstream Republican position hat "the President [must have] the flexibility to respond to terrorism on a moment's notice" and "be able to shift resources, including personnel, at the blink of an eye." He reasoned that civil-service rules that protect incompetent bureaucrats in backwater federal agencies such as the Department of Housing and Urban Development have no place in the nation's premier homeland security agency. He concluded that Senate Democrats were following not their best policy instincts but the dictates of the powerful union that represents federal employees, the American Federation of Government Employees.

Just before the elections, an increasingly frustrated Miller lashed out at his Democratic colleagues, predicting his party would suffer electoral losses due to its unwavering subservience to the federal employee union. Indeed, Miller's own constituents arrived at precisely this conclusion when they opted to replace Democratic union loyalist Sen. Max Cleland with GOP challenger Rep. Saxby Chambliss, after Chambliss highlighted 11 particularly revealing votes where Cleland put union interests ahead of national security. Congressional analyst Charlie Cook concluded that "the decision by Senate Democratic leaders to focus on workers' rights was . . . a costly miscalculation."

So why is liberal Minnesota Sen. Mark Dayton pulling his Democratic colleagues back into these treacherous waters? Last week, Dayton offered an amendment to the funding bill for the Department of Homeland Security that would have had the federal government dictating the compensation packages offered to private guards who provide security for federal buildings. Decrying the "cold-blooded profiteering" of private firms that offer security services without having to shoulder the burden of expensive mandates on employment, Dayton was trying to further the time-honored union strategy of using federal law to impose union-style mandates on non-union labor, thereby eliminating the ability of these firms to deliver higher quality service at less cost to the taxpayers.

Republican Sen. Thad Cochran (Miss.) objected, arguing that Dayton's amendment would have "a very serious adverse effect" on the government's ability "to ensure the security of federal buildings throughout the country." Notwithstanding the lessons of 2002, the vote broke down along party lines, as Dayton received the support of every Democrat (except Zell Miller, of course).

Meanwhile, on the other side of the Capitol, union interests prevailed when 24 House Republicans joined the overwhelming majority of Democrats to bar the White House from attempting to transfer hundreds of thousands of federal jobs to the private sector. Conservatives have long argued that many government workers perform duties--such as janitorial work, landscaping and copying services--that are not "inherently governmental" and are best left to more efficient and productive private-sector firms. Not surprisingly, the Bush Administration's laudable initiative to transfer these duties to private firms has encountered intense opposition from public employee unions and their allies on Capitol Hill.

Ernest Istook (R.-Okla.) who chairs the House Appropriations subcommittee that oversees this issue, fought valiantly, but unsuccessfully, to defeat the union-backed amendment offered by Maryland Democrat Chris Van Hollen. "The goal of so many members of this body," Istook complained, "is to shut down any effort to make the federal government more competitive and more efficient because they want to make sure that people are on the government payroll, even if it costs more to do the work, and even if it is less efficient." Bush Administration lobbyists hope to drop this provision from the final negotiated House-Senate agreement, but the damage has already been done. collective-bargaining "protections" were included in the Department of Defense spending bill recently signed by Bush.

These two episodes illustrate how far public employee unions will go to protect union jobs--even if it burdens taxpayers with unnecessary costs or interferes with national security.

Mr. Franc, who has held a number of positions on Capitol Hill, is vice president of Government Relations at the Heritage Foundation.