US fiscal time bomb is about to explode. Here's how to defuse it.

American leaders on the left and right are increasingly acknowledging that unless we take dramatic steps to reduce our deficits and debt, we may face not just another economic crisis but the end of American prosperity and leadership as we know it.

No one knows precisely when we will reach this economic tipping point, but I would argue we have no more than five years to put ourselves on a sustainable course. Change on this scale does not happen overnight. The time to start making hard choices is now.

The urgency of this threat has been explained well by two leading economists, Kenneth Rogoff, former chief economist at the International Monetary Fund, and Carmen Reinhart, of the University of Maryland. They argue that when the ratio of debt to gross domestic product (GDP) reaches 90 percent in an advanced economy like ours, economic growth slows considerably – at least 1 percent annually – while interest rates and inflation rise.

Under President Obama's own budget, we will reach this tipping point in 2020 according to the Congressional Budget Office. However, if you reject Washington's Enron-style accounting and include the money we steal from the Medicare and Social Security trust funds, our total "gross debt" will reach 91 percent of GDP this year.

The only way to avoid this crisis is to cut spending, raise taxes, or reform entitlements.

Unfortunately, history shows that the preferred choice of Congress is to raise taxes and avoid the hard work of prioritizing spending and reforming entitlement programs.

Option No. 1: Raise taxes

Congress has raised the payroll tax that funds Social Security 20 times, while the tax that helps fund the hospital insurance portion of Medicare has been raised eight times. Unless the American people demand that Congress take a different approach, we will once again see politicians propose new taxes, such as a value-added tax (VAT), to avoid a catastrophe.

In spite of Congress's tendency to raise taxes and put off reform for another day, I'm optimistic that the scope of our long-term debt problem will lead to true spending restraint and reform.

First, we've run out of taxpayers. There simply are not enough workers per retiree to fund the status quo. Taxes would have to be raised to wildly unrealistic levels – rates would have to double – to keep these programs afloat.

Second, the American people will not tolerate tax increases while Congress squanders at least $350 billion every year in wasteful, duplicative, and inefficient spending.

Option No. 2: Cut spending

It's true that cutting spending alone won't solve all of our problems but it is the place we must start. The American people will never trust Congress, an institution with an approval rating of 20 percent, to reform entitlement programs when we spend billions on failing programs and earmarks that benefit no one other than a member of Congress and a campaign contributor.

Those who claim it is too hard to cut domestic spending are misreading the electorate and misrepresenting history.

Over the past decade, federal spending has doubled. Yet few Americans would say we're better off.

If politicians in Washington had the will, the American people would back an effort that deemed much of the past growth in government as gratuitous, unnecessary, and reversible. In fact, 53 percent of the likely voters in a January Rasmussen poll said cutting spending would help the economy.

Third, politicians in Washington are already moving in this direction. New members such as Republican Sen. Scott Brown are being elected in "big government" strongholds like Massachusetts, and incumbents are warming to the idea of spending restraint.

For instance, the Senate recently came within two votes of paying for an extension of unemployment benefits with reductions in spending instead of borrowing more money from future generations.

Also, the number of members of Congress seeking earmarks – the gateway drug to spending addiction in Washington – is declining.

Option No. 3: Reform entitlement programs

Finally, members of Congress are increasingly willing to touch "third rail" issues such as Social Security, Medicare, and Medicaid, which are driving our unsustainable deficits.

Last year, I introduced a comprehensive health-care reform bill, the Patients' Choice Act, with Sen. Richard Burr (R) of North Carolina, and Reps. Paul Ryan (R) of Wisconsin and Devin Nunes (R) of California.

It is the antithesis of ObamaCare. Instead of building on a broken system, it would renovate a broken system and put the individual, not the government, in charge of his or her own health care.

Representative Ryan also has a more comprehensive plan called "A Roadmap for America's Future," which is a serious, specific proposal to put our major entitlement programs on a sustainable path.

Sen. Jim DeMint (R) of South Carolina has an innovative plan to save Social Security. Sens. Judd Gregg (R) of New Hampshire and Ron Wyden (D) of Washington have a bold plan to simplify our tax codes and lower tax rates.

I'm also drafting a plan that will lay out 12 specific steps to break Congress's addiction to spending. What is lacking in Washington is not solutions, but the courage and political will to enact real change.

Over the next two election cycles, the American people have an opportunity to mount a historic and heroic rescue of the American experiment. This is not a Republican or Democratic challenge. It is an American challenge. None of these challenges are insurmountable, but the time for action is now.

Tom Coburn, a physician and Republican senator from Oklahoma, is a member of the president's debt commission.