Now, despite small annual improvements, the deficit for the fiscal year that ends on Sunday will surpass $1 trillion for the fourth straight time. Against that headline-grabbing figure, Mr. Obama’s explanation — that the deficit he inherited is actually on a path to be cut in half just a year later than he promised, measured as a percentage of the economy’s total output — risks sounding professorial at best.

The fiscal imbalance on Mr. Obama’s watch, however much a result of economic and demographic factors beyond his control as well as his own policy choices, has increased the nation’s accumulated debt by about 40 percent and has saddled him with one of his biggest vulnerabilities. Facing off against Mitt Romney, Mr. Obama is on the defensive over deficits and debt nearly as much as he is over unemployment…

Mr. Obama wants to combine spending cuts and tax increases on upper-income households to close the fiscal hole without fundamentally reducing the role of government or altering the government guarantees at the heart of Medicare, Medicaid and Social Security. Those programs account for 40 percent of federal spending, and they will grow to half in a decade as more baby boomers claim benefits.