Despite a mandate to avoid deficits, the post office loses up to $15 billion a year, Issa told CNBC during an informal gathering of senior House Oversight and Government Reform Committee members.

"It's a combination of delivering what people want at a price they're willing to pay," the California Republican said. "We've restricted what the post office can charge for various classes of mail. But the biggest challenge is there are about 660,000 workers at the post office. In the private sector there would be about 400,000."

Though Issa's numbers are likely on the high side — the most recent official estimates from the postal service put the total employees at 574,000— reducing the size of the workforce and consolidating operations has been a priority.

Figuring out where the waste lies and streamlining operations are assignments for those who oversee the service, which receives no taxpayer funding despite being supervised by the government.

"It's not a debate about whether we need to get to that number. It's about how we get there," Issa said. "Do we get there by inducing retirements and finding ways to trim that workforce? Or do we wait for people to retire from an organization that has three fulltime employees that are 98 years old, literally."