House Republicans announced on Friday the latest in a long line of hare-brained schemes for funding the Highway Trust Fund, which is projected to become insolvent in August. Their ingenious proposal is to pay for transportation by making cuts at the post office.

This idea didn’t come from some Tea Party fringe of the GOP. It came straight from leadership: House Speaker John Boehner, Majority Leader Eric Cantor, and Majority Whip Kevin McCarthy.

In a memo to party members, they called the plan “the best way to ensure continued funding of highway projects in a fiscally responsible manner.” They say they can extend the current transportation bill by one year and offset the cost by reducing Saturday delivery. The proposal would save an estimated $10.7 billion over 10 years. Republicans have chided Democrats for offsetting MAP-21 — a two-year bill — with 10 years’ worth of savings, but now they seem prepared to do it themselves.

The other part of the GOP proposal would transfer funds from the Leaking Underground Storage Tank Trust Fund — also pillaged for MAP-21 — to the HTF. The LUST Trust Fund gets revenue from 0.1 cent of the 18.4-cent federal gas tax, but underground fuel storage tanks must be pretty leakproof lately because the fund is flush with money.

Altogether, the proposal would come up with between $14 and $15 billion to fill the gap between transportation spending and Highway Trust Fund receipts.

For the past few years, the idea of eliminating or reducing Saturday mail delivery has come up a number of times. But under those proposals, the savings would shore up the financially shaky U.S. Postal Service itself, which has lost $41 billion in the last six years — not transportation.

The Senate EPW Committee has unanimously passed a six-year transportation bill, though that committee has no idea how the bill would be paid for and is counting on the Finance Committee to come up with a solution. Just about everyone with a dog in the fight, including the reform coalition, is pushing hard for a long-term bill. A one-year extension, no matter how it’s funded, is a highly unpopular option.

The House GOP’s extension is especially unpopular because of the way it’s funded. Democrats have called it “strange,” “unworkable,” and a “non-starter.” The mail carriers’ union said the proposal “would begin dismantling the Postal Service” and “wouldn’t even work if tried.” Even the Greeting Card Association has taken a stand, calling the plan “misguided.”

Looks like yet another GOP funding gimmick destined for the dustbin.

Not that Republicans have cornered the market on transportation funding gimmicks, of course.