WASHINGTON — The Department of Homeland Security, apparently ready to cut its losses on a so-called invisible fence along the U.S.-Mexico border, has decided not to exercise a one-year option for Boeing to continue work on the troubled multibillion-dollar plan involving high-tech cameras, radar and vibration sensors.

The result, after an investment of more than $1 billion, may be a system with only 53 miles of unreliable coverage along the nearly 2,000-mile border.

The virtual fence was intended to link advanced monitoring technologies to command centers for Border Patrol to identify and thwart human trafficking and drug smuggling. But from the beginning, the program has been plagued by missed deadlines and the limitations of existing electronics in rugged, unpredictable wilderness where high winds and a tumbleweed can be enough to trigger an alarm.

Homeland Security officials decided on Sept. 21 not to invoke the department’s option with Boeing, the principle contractor on the project, and instead extended the deal only to mid-November, Boeing officials confirmed this week. Boeing has charged DHS more than $850 million since the project began in 2006.

The two-month Boeing extension about to run out, several members of Congress expect DHS to rule soon on the fate of the invisible fence, the hi-tech portion of the $4.4 billion Secure Border Initiative.

DHS spokesman Matt Chandler would only say a new way forward for the program “”is expected shortly.””

But given that the virtual fence has yet to pass muster even in the 53-mile test area — two sections in Arizona that officials acknowledge won’t be fully operational until 2013 — and the government’s lack of interest in extending Boeing’s contract, most do not expect DHS to invest billions more in a project that has continually disappointed.

Rep. Bennie Thompson, D-Miss., chairman of the House Homeland Security Committee, said he hopes DHS Secretary Janet Napolitano acts soon. “”The program is headed in the wrong direction,”” Thompson said.