Washington, D.C. ? The Bush administration has failed to fill roughly a quarter of the top leadership posts at the Department of Homeland Security, creating a “gaping hole” in the nation’s preparedness for a terrorist attack or other threat, according to a congressional report to be released today.

As of May 1, Homeland Security had 138 vacancies among its top 575 positions, with the greatest voids reported in its policy, legal and intelligence sections, as well as immigration agencies, the Federal Emergency Management Agency and the U.S. Coast Guard. The vacant slots include presidential, senior executive and other high-level appointments, according to the report by the House Homeland Security Committee.

A DHS spokesman challenged the report’s tally, saying that it was skewed by a sudden expansion this spring in the number of top management jobs.

The findings have stoked fresh concern among some in Congress about the four-year-old department’s progress in overcoming management problems.