Have heard that, but at least one credit agency says otherwise, so they obviously are listening to the Obama admin saying there isn’t enough money. Not worth the risk.
FY2013 interest on the debt is ~$415B, FY2013 tax receipts through July are ~$1.8T.
There’s enough money coming in to meet debt obligations. There is no need to raise the debt ceiling other than to enable greater debt.
http://www.treasurydirect.gov/govt/reports/ir/ir_expense.htm
http://www.cbo.gov/publication/44495