WASHINGTON (MarketWatch) - The U.S. government expects to borrow $59 billion in the April-June quarter, an estimate that is $66 billion higher than previously projected in February, the Treasury Department said Monday. The department had previously said it was going to pay down $7 billion of existing debt. The increase in borrowing in the current quarter is due to changes in cash balance assumptions that was partly offset by a drop in financing needs, the department said. The estimate includes an assumption of an end-of-June cash balance of $260 billion. For the July-September quarter, Treasury expects to borrow $66 billion in net marketable debt assuming a cash balance of $175 billion. During the January-March quarter, Treasury issued $141 billion in net marketable debt and ended with a cash balance of $100 billion. The department will announce on Wednesday the sizes and terms of the auction it holds four times a year to finance part of the debt. Congress has until late October or early November to raise the debt ceiling, according to estimates.