Everett Dirksen, the late Republican senator from Illinois, is famous for saying (on “The Tonight Show Starring Johnny Carson,” of all places) about government spending, “a billion here, a billion there and the first thing you know, you’re talking about real money.”

The senator died in 1969, when the national debt stood at $352.7 billion ($2.214 trillion in 2012 dollars, as measured by the CPI), and equal to 39 percent of 1969 GDP. Today, 43 mostly prosperous years later (many of them exceedingly so), the national debt is over $16 trillion–eight times as great in constant dollars–and two and half times as great in terms of GDP.

You’d think it might be an issue in the present campaign. But President Obama is not concerned. Indeed, he is so unconcerned that he can’t even remember what the size of the debt is these days. On “The Late Show with David Letterman” (these late-night talk shows, it seems, have become the agora of modern American politics), Letterman asked if it was now about $10 trillion. That, in fact, was the figure when Obama became president. Today, three and a half years later, it has grown by 60 percent, but Obama can’t remember exactly what it is. My friends at Power Line have the tape.

If Obama is re-elected he will have to be concerned at some point, such as when, to paraphrase Secretary of the Treasury Timothy Geithner, the government holds a bond auction and nobody shows up.