President Barack Obama's 2012 budget proposal projects this year's deficit will reach $1.6 trillion, the largest on record, as December's tax-cut deal begins to reduce federal revenues, a senior Democrat said Sunday.

The new forecast is larger than the $1.48 trillion deficit projected last month by the Congressional Budget Office, Congress's nonpartisan scorekeeper, and up from last year's $1.3 trillion shortfall. The tax deal extended tax cuts enacted during the Bush administration while adding others, such as a temporary...