The figure easily surpassed last year's $375 billion, making it the largest-ever in dollar terms. That gave ammunition to Democrats who say Mr. Bush's tax cuts and failure to prevent a loss of jobs during his term has worsened the outlook for the budget and the economy.
But in a political plus for Republicans, the new projection was also an improvement over forecasters' expectations of earlier this year. In February, the administration projected a $521 billion shortfall for 2004, while the nonpartisan Congressional Budget Office estimated a month earlier that the deficit would be $477 billion.
The White House was attributing the improvement to the collection of $82 billion more in revenue than had been anticipated, which generally reflects more vigorous economic activity. That was partly offset by $6 billion more in spending than was expected, mostly for Medicaid and Medicare.
"We are meeting our national priorities and by showing spending restraint elsewhere in the budget we are on track to meet the president's commitment to cutting deficits in half" over the next five years, White House spokesman Scott McClellan told reporters aboard Air Force One as Mr. Bush flew to campaign stops in the Midwest.
Democrats argue the report underscores the decline of the government's fiscal health under Mr. Bush, who has seen three straight years of worsening annual shortfalls following four consecutive surpluses under President Clinton.
"Anyway you slice it, a deficit exceeding $400 billion this year alone is bad news for the country," said Thomas Kahn, Democratic staff director for the House Budget Committee. "Republicans' failed budget policies have converted record surpluses into the biggest deficits in American history."
The White House was also boosting its estimate of Medicare spending by $67 billion over the next five years. Administration officials attributed the increase to added expenditures under last year's bill expanding Medicare coverage and to changes in long-range technical estimates about the program.
Medicare, the government's health insurance program for the elderly and disabled, spends about $300 billion a year. Extra Medicare spending could further heighten concerns about the program's solvency, already in jeopardy over the next two decades with the impending retirement of the huge baby-boom generation.
Medicare's anticipated rapid growth in coming years is expected to be a major engine keeping the budget in the red.
The federal budget year runs through Sept. 30. That means the final deficit figure will be available shortly before the Nov. 2 election, further shining a spotlight on the issue.