See the message below from Oppenheimer. The opinions are from their guy.
This is probably repetitious for most of you, but here are the key dates for the debt ceiling/default calendar:
10/17: Treasury says they will be out of borrowing authority. They will still have 25 to 30 bln in cash that will keep the government going, but new auctions will be suspended. Bill maturities will likely be paid through 10/31 from incoming revenues.
10/21: The first auctions that will have been cancelled -- there will be no 3 or 6 month bills issued and the 1 month bill auction scheduled for ther 22nd will be cancelled.
10/24: The announcement for new 2s, 5s and 7s. If no debt ceiling deal is reached, these will be postponed.
10/31: Coupon and maturity payments are due. Most economists project that the Treasury will have enough money to make these payments.
11/1: $70 bln of Social Security and Medicare payments are due. There is no way the Treasury will be able to make these payments. To me this will be the breaking point for Congress, as the outrage would be unimaginable.