(Adds Republican reaction, CBO report on Senate measure)

By Jeremy Pelofsky

WASHINGTON, Jan 26 (Reuters) - The Democratic stimulus package the U.S. Congress will weigh on Wednesday falls billions of dollars short of President Barack Obama's goal to pump most of the money into the economy quickly, a report released on Monday showed.

The $816 billion package will pour some $525.5 billion, or 64 percent, via spending and tax cuts into the ailing economy within 19 months, according to the report issued late on Monday by the non-partisan Congressional Budget Office.

Last week, Obama's budget director, Peter Orszag, told lawmakers the administration's goal was to pump at least 75 percent of the money from the stimulus package into the economy by Sept. 30, 2010.

The report expands on another from the same office Republicans had touted last week as showing that less than 40 percent of the stimulus money would filter into the economy over the 19-month period. Democrats complained report was a partial review and CBO on Monday concurred.

The legislation "provides immediate stimulus to help create jobs and makes long-term, targeted, and responsible investments to keep our nation's economy growing for years to come," House of Representatives Speaker Nancy Pelosi said in a statement.

Republicans seized on the report as evidence the Democrats' spending plan would take too long to help the economy.

"Once again, it highlights the fact that a huge chunk of the Democrats' so-called stimulus plan comes way too late to make any real difference in fixing the economy," said Kevin Smith, a spokesman for House Minority Leader John Boehner.