There was also no immediate hope for reopening the U.S. government, which enters a third week of partial shutdown on Tuesday.
Sen. Joe Manchin says investors are growing increasingly "skittish" about the possibility of default. The West Virginia Democrat is part of a bipartisan group of 12 senators pushing a proposal to re-open the government and fund it at current levels for six months while raising the debt limit through Jan. 31.
Negotiations to clear a path for a new budget agreement ended Sunday at an impasse.
Earnings season goes into high gear this week. Coca-Cola, Johnson & Johnson and Citigroup report results Tuesday.
Bond trading is closed Monday for Columbus Day.