RPT-FACTBOX-Nitty gritty on the White House's new forecast

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Aug 20 (Reuters) - The Obama administration plans to trim its projection for the fiscal 2009 budget deficit next week to $1.58 trillion from $1.84 trillion, administration officials said.

Below are a few facts about the new number and why it is being revised:

* The main reason for drop in the projected deficit is the elimination of a $250 billion "placeholder" that had been set aside in previous budget forecasts for potential future bank rescues.

* Another $78 billion set aside for the Federal Deposit Insurance Corp to pay for bank failures also will be saved because fewer banks went under than first expected.

* U.S. officials said spending in the 2009 fiscal year would total $3.653 trillion and revenues would be $2.074 trillion.

* The $1.58 trillion deficit would account for 11.2 percent of U.S. gross domestic product -- the highest deficit as a percentage of GDP since 1945.

* In May, the White House pushed up its budget deficit estimates for 2009 to $1.84 trillion -- representing 12.9 percent of GDP.

A White House forecast released in February projected a deficit of $1.75 trillion, or 12.3 percent of GDP.

The 2009 fiscal year ends on Sept. 30.

(Compiled by Jeff Mason; Editing by Bill Trott)