The Capitol Police department is poised to replace its outdated and unreliable radio system, after President Barack Obama recently signed a war supplemental that includes funding for the project.

Police officials have argued for years that the radios need to be replaced, but Congress has been slow in funding such an expensive project. The current estimate for the project totals almost $100 million — about $65 million more than the original proposal.

Most of that funding is now secure. The Iraq and Afghanistan supplemental spending bill includes about $70 million to replace the radios, paving the way for the department to start a three-year process. They hope to complete it in 2012.

But there’s one catch: For every dollar spent, police officials have to clear an “obligation plan— with the House and Senate Appropriations committees.

Such approval has slowed down the process in the past. About a year ago, the House Appropriations Subcommittee on the Legislative Branch halted upgrade plans after the cost estimate jumped from $35 million to $70 million.

Chairwoman Debbie Wasserman Schultz (D-Fla.) has said she is now “comfortable— with the price, though she and other committee members have expressed concern that it would increase if unchecked. Senate appropriators, meanwhile, have questioned the price but have been more or less supportive.

A design study for the project — which is due for completion in a few months — might also add new specifications and cost to the project.

Appropriators thus requested that the supplemental funds for radios be fenced off, or given out on the condition of committee approval.

Still, police officials hope the sudden influx of funds will jump-start a process that has dragged on for years. They plan to hand over their first obligation plan to committees later this summer.

In the past, appropriators have balked at the expense of the system, which will only last about 15 years. Part of the problem is the uniqueness of the Capitol — police need to be able to use radios inside thick marble walls and in underground subways.

In the meantime, the department’s radios have gotten so out of date that the manufacturer can no longer provide technical support.

“These circumstances create a substantive risk to our ability to properly carry out our mission, especially during a time of emergency,— Capitol Police Chief Phillip Morse said in recent testimony to Members. The system, he added, “may present an unacceptably high risk to the life and safety— of those on Capitol Hill.

The department is one of the last local agencies to switch over to digital, leaving conversations open to anyone with a store-bought scanner. As it stands, Capitol Police officers can’t communicate with officers from agencies such as the Metropolitan Police Department. Their radios are incompatible.

Replacing the radios will change all that, Capitol Police spokeswoman Kimberly Schneider said. New radios, she said in an e-mail, will improve “our ability to fulfill our security mission of protecting the Capitol Complex, Congress and its legislative process.—

“Officer safety will be improved as radio communication within buildings and in underground areas will be reliable and secure,— she said.