In a stinging rebuke, members of Congress from both parties are challenging a $17-billion plan that the Bush administration put on a fast track earlier this year to secure the nation’s cyber networks from terror threats and spying.

Critics say the administration’s plan to label virtually every part of the project as classified would make adequate oversight impossible. They also complain that some of the technologies poised to receive funding are “not mature” and that some projects deal more with foreign intelligence collection than with protecting America’s computer systems.

Those systems have grown in recent years to manage nearly all aspects of life, including the flow of electricity, commerce and information.

“For all its ambitions, the cyber initiative sidesteps some of the most important issues that must be addressed to develop the means to defend the country,” members of the Senate Armed Services Committee wrote in a report released last week.

In January, President Bush created the initiative, described by intelligence professionals as one of extraordinary scope that will rival in importance the Manhattan Project, the World War II-era effort to build the first atomic bomb.

The initiative draws on significant support from the National Security Agency and includes:

nCreating a National Cybersecurity Center, akin to the National Counterterrorism Center that coordinates the resources and activities of numerous government agencies.