"A penny for your thoughts?"

How quaint. A penny just isn't what it was when English poet and playwright John Heywood penned the phrase in 1546.

Or is it?

Last May, Rep. Connie Mack of Florida introduced legislation (H.R. 1848) to balance the federal budget using nothing more than the power of a penny. The measure, widely known as the Mack Penny Plan, would balance the budget by cutting federal spending (excluding net interest) 1 percent — one penny out of every dollar — each year for six consecutive years and capping total federal spending at 18 percent of gross domestic product starting in fiscal year 2018.

The problem Mack proposes to solve is immense. Last year the federal government spent $3.6 trillion, borrowing 36 cents of every dollar it spent. The Congressional Budget Office estimates the cumulative budget deficit could total as much as $8.5 trillion over the coming decade.

Worse yet, those deficits accumulate even as the tax burden rises. Federal revenue averaged 18 percent of GDP from 1980 to 2010.

If the Bush tax cuts and other tax provisions expire next year as scheduled, federal revenue will rise to more than 20 percent of GDP in fiscal year 2014 and to 20.9 percent by fiscal year 2021 — tying the record set during World War II.

And contrary to popular belief, even if the Bush tax cuts and other expiring tax provisions are extended, the federal tax burden is slated to increase above the historical average of 18 percent.

Is it possible to balance the budget without raising taxes? The Mack Penny Plan shows not only is that possible, but it's possible to balance the budget while cutting the tax burden to its 30-year historical average. The math is indisputable.

The Mack Penny Plan, however, won't do away with the need for Congress to make tough choices. Federal spending is on course to grow nearly 46 percent over the next decade. Mack's legislation would limit the increase to about 19 percent.

Is it realistic to think Congress could limit federal spending to 18 percent of GDP?

Actually, there is precedent. Federal spending fell as a share of GDP for nine consecutive years before bottoming out at 18.2 percent of GDP in fiscal years 2000 and 2001. The Mack Penny Plan would return federal spending, expressed as a share of GDP, near the level achieved during the last two years of the Clinton administration.

Obviously, the world is a very different place than it was at the end of the Clinton administration. Heightened global challenges make it necessary for the U.S. to spend more on national defense and homeland security. The aging of the Baby Boom population, moreover, will increasingly strain the federal budget.

But either Congress will resize the federal government's responsibilities and reform its programs or, by refusing to change course, it will lead this country into bankruptcy. As David Walker, U.S. comptroller general from 1998 to 2008, warned last summer: "We are heading for a fiscal abyss at breakneck speed. We must change course."

Some argue it's not necessary to balance the federal budget. Indeed, many economists say Congress' objective should be simply to stabilize the debt-to-GDP ratio. And you could argue capping spending at 18 percent of GDP is too ambitious given the federal government's responsibilities.

Nonetheless, the Mack Penny Plan has attracted 70 co-sponsors in the House and eight supporters in the Senate because it offers an inspired vision for putting the federal budget on the path to solvency. "To grasp and hold a vision," President Ronald Reagan said, "that is the very essence of successful leadership."

A penny for your thoughts?

Congress would be unwise to overlook the value of a penny … or of the Mack Penny Plan.

James Carter of Vienna, Va., was a deputy assistant secretary of the U.S. Treasury under President George W. Bush and served on the staff of the Senate Budget Committee.