Early Thursday morning, Potomac Research Group analyst Greg Valliere predicted that if the debt-ceiling deadline grew closer, President Barack Obama would play his "trump card" in the debate. He would remind seniors that if Congress doesn't raise the debt ceiling, seniors wouldn't get their Social Security checks.

"GOP strategists like Karl Rove surely know that it's just a matter of time before President Obama throws a game-changer — warning senior citizens that their Social Security checks won't be mailed because of John Boehner," Valliere wrote in a note to clients.

A few hours later, Obama did just that during a speech at M. Luis Construction Company in Rockville, Md. He spent much of the speech warning that while the ongoing government shutdown was damaging, failure to raise the debt ceiling by an Oct. 17 deadline would be even worse.

"In a government shutdown, Social Security checks still go out on time. In an economic shutdown — if we don't raise the debt ceiling — they don't go out on time," Obama said. "In a government shutdown, disability benefits still arrive on time. In an economic shutdown, they don't."

Earlier on Thursday, the Treasury Department warned in a big report that breaching the debt ceiling could inflict economic calamity "more severe than any seen since the Great Depression."

"The United States has never defaulted on its obligations, and the U.S. dollar and Treasury securities are at the center of the international financial system," the report said.

"A default would be unprecedented and has the potential to be catastrophic: credit markets could freeze, the value of the dollar could plummet, U.S. interest rates could skyrocket, the negative spillovers could reverberate around the world, and there might be a financial crisis and recession that could echo the events of 2008 or worse."

The Treasury says that the debt ceiling needs to be raised by Oct. 17 to avoid potential default on some U.S. obligations. After that date, the Treasury would have only approximately $30 billion to meet all of its commitments. On some days, expenditures can go as high as $60 billion.

Obama says that he won't negotiate over raising the debt ceiling, calling it Congress' responsibility. House Republicans, meanwhile, have looked to extract some kind of concession out of Obama in exchange for a debt-ceiling hike.

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