While Members of Congress and presidential candidates have been busy beating each other up over whether millionaires are job creators or job destroyers, they have lost sight of who really spurs America’s economic growth. It’s not the fat cats on Wall Street. It’s the smart cats in the research laboratories.

Last year’s budget gridlock gave the smart cats little confidence that lawmakers understood the fragile nature of the scientific enterprise. And if the second session of the 112th Congress is simply a rerun of last year’s horror show, the uncertainties it will create could easily cause our nation’s innovation engine to sputter badly.

To be successful, scientists require patient capital and dependable policies. And for more than half a century, America provided those essentials. In return, science provided America with jobs and wealth.

Economists estimate that since the end of World War II, more than 50 percent of our nation’s gross domestic product increase has stemmed from science, technology, engineering and mathematics. Today, they say, STEM is the driver of 70 percent of our nation’s economic growth.

Until recently, we were the lion in the global research kingdom. We led the world in scientific discovery and innovation. We had the brains, the money and the political will to keep us at the cutting edge. But the rest of the world has been catching up, and there are signs we are now being overtaken.

Three independent assessments released last year — “The Global Innovation Index,” a joint international study led by INSEAD, an international graduate business school; “The Atlantic Century II,” a survey by the Information Technology and Innovation Foundation; and the “Global Competitiveness Report,” an annual study by the World Economic Forum — document our fall from the top. They rank us between fourth and ninth in innovation. And the ITIF assessment ranks us next to last in innovation gains among 44 leading nations.

Seven years ago, New York Times columnist Thomas Friedman punctured America’s psyche of exceptionalism when he wrote “The World is Flat: A Brief History of the Twenty-First Century.” Friedman illustrated how globalization, driven by technological advances, had snapped America’s reins over the world’s economy.

The world Friedman encountered on his travels around the globe was vastly different from the world Tom Brokaw had described in “The Greatest Generation.”

In a 2011 sequel, “That Used to Be Us,” which he co-authored with Michael Mandelbaum, Friedman described how the world we invented had overtaken us. He gave literary voice to the stark data the innovation assessments provide.

Friedman and Mandelbaum’s message is simple: America, we have a problem.

That warning should not be news to Congress or the White House. Norman Augustine, retired CEO of Lockheed Martin, has been sounding the same alarm for more than a decade. And although legislators responded to the National Academies report, “Rising Above the Gathering Storm” — which Augustine led — by passing the America Competes Act in 2005, the bill’s authorizations gave rise to false hopes.

The bipartisan legislation provided a compelling economic rationale and an aggressive road map for doubling the budgets of three key science agencies: the Department of Energy’s Office of Science, the National Institute of Standards and Technology’s Core Program and the National Science Foundation.

But the budget follow-through fell through. Confronted with an array of competing needs, unforeseen emergencies and partisan jousting over deficits, debt and revenues, appropriators were unable to make good on the financial goods.

With last year’s budgetary battle scars still stinging, it’s hard to see how lawmakers this year will have the will to provide the financial fuel the innovation engine desperately requires. In an election year, it’s hard to see how they will put pernicious partisanship aside and strike a chord of compromise to afford research laboratories with the financial certainty they require. With dysfunction becoming ingrained in the Congressional consciousness, it’s hard to see how they will avoid deferring difficult decisions until after the public has rendered its electoral judgment.

But if policymakers don’t get serious about innovation soon, they will foreclose our nation’s ability to compete in the global marketplace of the 21st century. Our competitors won’t take a siesta if we take a pass on science.

As Apple demonstrated with the iPhone and the iPad, creative industrialists, such as Steve Jobs, can turn federally funded scientific discoveries into marketable products, creating jobs, rewarding investors and transforming the lives of tens of millions of people.

But in today’s world of instant financial gratification, industry cannot provide the patient capital science needs. That capital must come from the American taxpayer. And it’s not at all inappropriate because, in the end, the American taxpayer is the beneficiary.

Michael S. Lubell is a professor of physics at the City College of the City University of New York and director of public affairs of the American Physical Society.