The Treasury Department is seeking to borrow $331 billion through September if Congress raises the nation's borrowing limit this week.
Congress is expected to vote Monday on a deal supported by President Barack Obama and congressional leaders from both parties. The deal would extend the current $14.3 trillion debt ceiling by up to $2.4 trillion and pare federal spending by more than $2 trillion over the next 10 years.
Treasury officials say they expect Congress will raise the borrowing limit before Tuesday's midnight deadline. That would clear the way for the first auction on Aug. 9.
The latest estimate for the July-September borrowing needs is slightly lower than a May estimate of $405 billion. Treasury says the decrease is largely because of lower spending requirements and cash balance adjustments.