Federal agencies obligated more than $169 billion worth of contract spending last year — almost a third of federal contracting dollars — without first holding competitions among vendors, according to a Government Accountability Office report.

Those noncompetitive deals represented about 31 percent of contract obligations in 2009, down from 36 percent in 2005. During the same period, however, the percentage of competitive contracts attracting only a single bidder inched up from 12.5 percent to 13.3 percent.

About 45 percent of Navy's and Air Force's 2009 contract obligations were noncompetitive, compared to 7 percent of the Energy Department's.

Agencies are required by law — the 1984 Competition in Contracting Act — to hold full and open competition on the grounds that it leads to better deals for the government. After the Air Force encouraged competition on a contract for aluminum pallets, for example, the incumbent contractor found ways to deliver a better price and delivery schedules, the GAO report says.

But the act allows for exceptions and agencies have exploited those, sometimes skirting the Federal Acquisition Regulation in the process, the GAO found.

Over time, for example, the cost of a sole-source Army contract in support of the Chinook helicopter program ballooned from $35 million to about $477 million. Contrary to the FAR, the acquisition plan was not revised.

In some cases, program managers pressure contracting officials to avoid competition because they prefer certain vendors. At the National Institutes of Health, program officials "described their comfort with certain contractors because of their level of understanding of requirements and because they could be relied on to complete the work," the report says.

And in 27 out of 47 Defense Department contracts reviewed by the GAO, the government couldn't compete the work because it didn't have rights to proprietary technical data held by an existing contractor.

When the Air Force asked about the price of the technical data package for one aircraft program, the contractor and original manufacturer replied that it was not for sale. On another piece of Air Force business, the contractor put the cost of the data package at $1.3 billion, but refused to sell it.

Under legislation passed last year, however, the buying strategies for major weapons programs will have to consider acquiring data packages.

Among other recommendations, the GAO urged the Office of Management and Budget to consider revising the FAR to require agencies to "critically evaluate" the circumstances leading to only one bid being received on a particular contract and to identify steps to increase the odds of competition.

The GAO report was requested by the House Oversight and Government Reform Committee.