Washington ? Up to half the nation’s 1.8 million federal civilian workers eventually could find they have a new boss or, worse, no job.

The Bush administration is taking steps that could lead to the privatization of federal jobs at an unprecedented level, and officials proposed rules Thursday to make it easier for companies to compete with the government for maintenance, construction, secretarial and other work.

Employee unions raised strong objections, contending the administration was trying to help its business allies at the expense of workers’ rights. Bush officials said it was just a question of saving money.

“We want the best deal for the taxpayer. We want to provide the best service for the taxpayer,” said Angela Styles, federal procurement policy administrator for the White House’s Office of Management and Budget. “We think a key tool for doing that is through public-private competition.”

Republicans have long favored opening jobs to competition from outside government. They argue that competitive bidding will force bureaucracies to improve service and lower costs or lose business to the private sector.

The administration has identified as many as 850,000 federal jobs ” nearly half the government’s civilian work force ” that could be performed by the private sector. For now, Bush wants at least 15 percent of those opened to competition by October 2003.

The proposal comes on the heels of last week’s GOP victories in congressional elections, which raised White House hopes for Bush’s agenda. The White House also is poised to beat back union opposition to rules that would apply to workers in the new Homeland Security Department.

“The Bush administration officials are at war with reliable and experienced rank-and-file federal employees,” said Bobby L. Harnage Sr., president of the American Federation of Government Employees. “They are systematically conspiring to bust their unions, gut their civil service protections and hand over their jobs to politically well-connected contractors.”

The federal work force under Bush is growing again, largely because of homeland security needs, said Paul Light, senior fellow at The Brookings Institution. He estimates that the work force will rise again to 2 million in the next few years because of increased hiring for airport screeners, air marshals, border patrol agents and immigration inspectors.

Privatizing so many jobs helps protect the GOP against potential attacks from Democrats that the era of big government is back under Bush, said Light, who thinks Democrats will try to make that a campaign issue in 2004.

Sen. John Edwards, a Democratic presidential hopeful from North Carolina, called Tuesday for a 10 percent cut in the federal work force that is not involved in fighting terrorism.

Republicans “don’t want to be known as the party that increased the size of government going into a possible election campaign,” Light said. “I wouldn’t be surprised if they were to say they want to outsource or competitively source every job but the president and vice president.”

Traditional high-ranking government positions will not be opened for competition. Federal jobs that are opened to competition aren’t necessarily gone for good. The government could win service contracts over private businesses.

White House spokesman Scott McClellan sidestepped questions about whether government workers should fear for their jobs. “What we’re trying to do is make government work better for the American taxpayer.”

The Bush administration found “troubling” examples of work being performed by government employees that probably could be done better and more cheaply by private businesses, Styles said. For example, 540 Navy workers make eyeglasses. In the Parks Service, rangers are being used to take money and tickets at the front gates “instead of protecting our public lands and ensuring they are well taken care of,” she said.

The General Accounting Office has determined that public-private competition could save taxpayers 30 percent on each contract.

Current federal rules allow for public-private competition, but the regulations are so cumbersome that private firms are often reluctant to seek government contracts, officials said.

One reform would encourage agencies to complete competitive bid reviews within a year. Under current rules, the competitive bid process can take as long as four years ” a delay that scares off private sector bids, officials said. Another change is that the lowest bid won’t automatically win.

The proposed rules are subject to a 30-day public review period before they are implemented.

Expecting union fallout, the administration said the initiative encourages unions to compete and win contracts.

Bush picked this new fight with federal unions one day after it became clear that he had won another battle with them. With Republicans ready to take full control of Congress, Democrats were largely abandoning their demands for union protections at the new Department of Homeland Security.

The House easily passed a bill that would establish the department on Wednesday, and the Senate was ready to follow suit.