WASHINGTON - April 8, 2010 - As the U.S. census nears its final stages, the government is preparing for possible debacles that could derail its $15 billion head count, from mass identity theft and lawsuits to homeowners who refuse to answer their doors.

Census Bureau documents, obtained by The Associated Press, underscore the highly fragile nature of the high-stakes population count before the government dispatches some 700,000 temporary workers to visit homes, beginning in May.

The preparedness efforts are not entirely new. Previous censuses had contingency plans in place, at least conceptually, and the Census Bureau has never failed to meet its constitutional mandate of delivering population counts by December 31 each decennial year.

But this is the first time the Census has detailed - in 300 pages of internal documents released under the Freedom of Information Act - specific risks to the once-a-decade government count. It's part of the bureau's approach to handling threats that could undermine accuracy, omit large segments of the public or add to already ballooning costs.

Many of the documents proved telling, even with portions redacted or withheld for security reasons.

"Considering the volume of data that the Bureau of Census gathers during the census, some loss of confidential data is bound to occur," one document bluntly states. Citing past missteps, such as the loss of work laptops by census employees in 2006, it details a rapid-response effort that includes notification to authorities, if appropriate, as well as free credit monitoring for potential identity theft victims.