This year was supposed to be the time when President Obama and Congress would shift toward austerity. The competing budget proposals of congressional Republicans and the president do contain hints that such a moment has arrived -- but only by the sadly low standards of the current fiscal debate.

Obama's budget proposal, unveiled on Monday, calls for $1.1 trillion in spending cuts and tax increases over the next decade. The proposal projects that the deficit will fall from a post-war record 11 percent of GDP in the current fiscal year to 3.1 percent by 2021.

Sadly, a closer look suggests that the budget would have almost no chance of achieving this. First, according to Maya MacGuineas of the Committee for a Responsible Federal Budget, the projected fall in the deficit relies on rosy assumptions and "magic asterisks." By using more optimistic assumptions about underlying economic, revenue and spending growth than the nonpartisan Congressional Budget Office, it knocks an average of $150 billion a year off the deficit.

Obama's plans to raise taxes are also problematic. Last December he capitulated to Republicans and agreed to extend all of former President George W. Bush's tax cuts to 2012, including those for the rich. His budget proposes that the rich pay higher taxes thereafter. But the Republicans who control the House of Representatives are dead set against any tax increases.

Finally, Obama's budget largely ignores the real long-term deficit threat, which comes from the big three entitlements: Social Security, Medicare and Medicaid. These dominate mandatory spending, which does not require annual authorization. As the population ages, mandatory spending will grow relentlessly, to 14 percent of GDP by 2021 and much more thereafter.

Unfortunately, the Republicans are no braver on entitlements. House Republicans, bowing to pressure from their Tea Party wing, recently tripled the spending cuts they want for the remaining seven months of the fiscal year to $100 billion. But they come entirely from the discretionary budget.

The scale of cuts Republicans want would also undo a sizeable portion of the stimulus of last year's tax deal, setting back the recovery. For that reason, as well as others, Democrats are unlikely to go along.

Instead, the two sides will have to try and hammer out a compromise. Time is running out: The government's authority to spend money expires on March 4, and to issue additional debt as early as May.