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By JON KARL and SUNLEN MILLER

The leading Republican budget hawk in the Senate, Senator Tom Coburn, R-OK., is coming out Tuesday with a new book that provides a harsh critique of Congress and a dire warning for the future economic situation of the nation.

The picture Coburn paints in his new book, "The Debt Bomb: A Bold Plan to Stop Washington from Bankrupting America," is not a rosy one of the state of the U.S. Congress. He lambasts the upper chamber as a body that is "heavily sedated" and calls for 90% of the unproductive members to be fired.

"Congress today is a stagnant pond that needs to be drained and refilled with a steady stream of new public servants," he writes, according to excerpts provided to ABC News in advance of release.

"I'm a fan of the Jack Welch principle in reverse for Congress … fire 90 percent of members every election and only keep the 10 percent who were productive."

Coburn says that the "root of almost all that ails Washington," is careerism.

"Careerism is the dark matter of the political universe. It is the unseen force that bends decisions, and character, in ways that defy common sense and obvious explanations," he writes.  "If members of Congress knew their current term would be their last, I have no doubt we could defuse the debt bomb within a matter of days … Bridging the gap between conservatives and liberals is easy compared to bridging the gap between courage and cowardice. "

Coburn has himself spent 13 years in Congress; he was first elected to the House in 1995, as a 48-year-old doctor, and served three 2-year terms before declining to run for a fourth.  He was elected to the Senate a few years later, in 2004.

Coburn says that the federal debt is now so out of control that doing nothing "is a recipe for mutually assured destruction," for both parties, which will represent "real betrayal and the heresy" to their constituents.

He says the fiscal threat is greater to the nation, in no uncertain terms, than any foreign army or terrorist network.

The senator refers to the situation facing the nation as, the namesake of his book, a "debt bomb" that is in dire need of being diffused.

As a former doctor, Coburn provides a harsh prognosis - he says that if America were his patient, "I would tell her she had a 100 percent chance of experiencing a major cardiac event-a potentially fatal heart attack or stroke-if she failed to take immediate steps to get healthy."

Getting "healthy" for the nation means getting control of the nation's debts, he writes. Coburn warns that the nation will face a debt crisis within two years if a long-term deficit reduction plan is not enacted.

And neither party is immune from criticism.

"Democrats have used shameless class warfare rhetoric to advance the fiction that taxing the rich will solve our long-term debt problem," Coburn writes.  "Republicans, on the other hand, have desecrated the limited-government legacies of Reagan, Goldwater, and our founders by embarking on spending orgies with borrowed money-a form of deferred taxation and financial repression-while hiding beyond false pledges of tax purity that have made tax reduction and simplification much more difficult to achieve."

Doing nothing, he argues, will lead to massive tax increases and to benefit cuts in entitlement programs.

Coburn, however, says Republicans have already put revenue on the table.  The bigger obstacle, he writes,  is the refusal of Democrats to embrace entitlement reform.

"The days of universal entitlements as we've known them are over. Maintaining the status quo is a mathematical impossibility. Telling seniors otherwise is dishonest and will delay needed reforms," he writes. " Congressional leaders sometimes believe they are demonstrating their progressive purity by taking Social Security and entitlement reform off the table. The problem is, you can't take demographics off the table."

Coburn says that many in Congress and in the Obama administration understand the severity of the debt problem, yet few are willing to risk their political careers to solve the problem.

"Most politicians were content to sit in their partisan bunkers and cling to the illusion that they were holding a line, when the reality was, there were no more lines left to hold. Both parties had betrayed their core beliefs and positions. We were under siege and surrounded on all sides, not by a foreign army but by foreign creditors."

The book calls for members of Congress to break free of that false illusion and to face up to the "inescapable" choices that need to be made.