A bipartisan group of five prominent U.S. senators came out in support of an old idea on Tuesday: that America should do away with its paper-based dollar bills in favour of a $1 coin.

Republicans John McCain of Arizona, Tom Coburn of Oklahoma, Mike Enzi of Wyoming and Democrats Mark Udall of Colorado and Tom Harkin of Iowa have lent their name to a bill backing what consumer advocates have been arguing for years.

Led by former presidential candidate McCain, the Currency Optimization, Innovation and National Savings Act is currently making the rounds in Washington, with proponents hoping to collect enough support to make it law.

'Congress must look at every area of the federal government, big or small, to save money.' —Republican U.S. Senator John McCain

The argument boils down to economics. Although bills are cheaper to produce, they don't last nearly as long and as such are far more expensive to constantly reprint. Paper bills last for about three years, whereas coins can often remain in circulation for as long as 10 times that.

Numerous government studies have concluded over the past several decades that coins would be preferable. But past attempts at implementing a loonie for America — such as the now-defunct Susan B Anthony dollar and the Sacajawea dollar — have failed in part because those coins didn't replace bills, they were merely offered as an alternative that nobody understood.

The pitch this time comes on the back of a report co-authored by two Washington D.C. lobby groups, the Council for Citizens Against Government Waste and the Dollar Coin Alliance, that have come with a savings number that far outstretches previous estimates.

Phasing out dollar bills in favour of coins over a four-year period would save the U.S. government as much as $13.8 billion, the report says.

"With our nation’s debt now standing at $16.8 trillion, Congress must look at every area of the federal government, big or small, to save money," McCain told lawmakers this week. "And this simple bipartisan bill will do just that — save money."