Coming Up on 'This Week': Default Deadline - White House Senior Advisor David Plouffe, GOP Sen. Lindsey Graham

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The clock ticks closer to a U.S. government default as Congress goes down to the wire on raising the debt ceiling. Can political leaders avoid what President Obama has called a crisis of their own making?

Sunday on a special edition of "This Week," Christiane Amanpour speaks with White House Senior Advisor David Plouffe for the latest on the debt ceiling endgame. "Good Morning America" co-anchor and ABC News Chief Political Correspondent George Stephanopoulos also joins the conversation, and will contribute reporting and analysis throughout the program.

Then, Sen. Lindsey Graham, R-S.C., weighs in on whether the current deals under negotiation go far enough to get the U.S. fiscal house in order. After calling the original plan proposed by House Speaker John Boehner this week "a straight-jacket on real spending reform," can Graham get behind any plans on the table?

Will calls for a balanced budget amendment sink or save a final deal? And can the Senate and House finally reach an agreement before Aug. 2, when the U.S. loses the ability to borrow more funds? An exclusive interview with Sen. Lindsey Graham, only on "This Week."

As the global economy hangs in the balance, could the debt crisis trigger a double-dip recession? Christiane speaks with Dr. Mohamed El-Erian, CEO of investment management firm PIMCO on the consequences of a possible default by the world's largest economy, and the impact on the rest of the world.

And are politics putting the economy in peril? The "This Week" roundtable debates the impact of the debt ceiling battle and whether dysfunction in Washington has reached a new low. Christiane is joined by ABC News Chief Political Correspondent George Stephanopoulos, ABC's George Will, Nobel Prize-winning economist and New York Times columnist Paul Krugman, and Grover Norquist, President of Americans for Tax Reform.

Plus, the tragedy in Norway shines a new light on violent right-wing extremism, while here in the United States, another homegrown plot by a Muslim soldier to attack Ft. Hood is foiled. What are the ongoing dangers from extremists in the U.S., and are enough federal resources dedicated to the threat? Christiane speaks with New York City Police Commissioner Ray Kelly on whether U.S. law enforcement is prepared for potential dangers here at home from all fronts.

Finally, ABC News' David Muir is the only network anchor on the ground from the devastating drought and famine in the Horn of Africa. How are aid organizations grappling with the largest humanitarian disaster on Earth? "World News" weekend anchor David Muir brings his latest reporting to "This Week."