Jacob "Jack" Lew, U.S. treasury secretary, speaks during an Economic Club of Washington breakfast in Washington, D.C., in this Sept. 17, 2013 file photo. (Andrew Harrer/Bloomberg/Getty Images)

Treasury Secretary Jack Lew said today the nation will hit its borrowing limit on Oct. 17, when the treasury will have less than $30 billion to pay outstanding debts.

In a letter to members of Congress, Lew struck an urgent tone and asked lawmakers to raise the debt limit, which is now $16.7 trillion.

This is the first time Lew has provided Congress a specific deadline to raise the debt limit. Without Congressional action, he said, the cash on hand "would be far short of net expenditures on certain days, which can be as high as $60 billion."

"If we have insufficient cash on hand," Lew wrote, "it would be impossible for the United States of America to meet all of its obligations for the first time in our history."

"The United States should never have to choose, for example, whether to pay Social Security to seniors, pay benefits to our veterans, or make payments to state and local jurisdictions and health care providers under Medicare and Medicaid," Lew wrote.

"There is no way of knowing the damage any prioritization plan would have on our economy and financial markets," he added. "It would represent an irresponsible retreat from a core American value: We are a nation that honors all of its commitments."