The U.S. Senate has been debating a military funding bill that would require President Bush to begin withdrawing troops from Iraq in October.
The measure is expected to pass Thursday in the Democratic-controlled Senate.
The legislation sets a non-binding goal of withdrawing U.S. troops from Iraq by April of next year. It also sets benchmarks for Iraq's government to show progress in securing the country.
The Democratic-controlled U.S. House of Representatives approved a similar measure Wednesday.
White House spokeswoman Dana Perino said President Bush will veto the legislation "very soon" after it arrives on his desk. The House measure lacked the two-thirds majority needed to override a veto, and the Senate measure is not expected to have enough votes to override a veto, either.
The Senate bill includes some $95 billion to fund military operations in Iraq and Afghanistan through the end of September.
Some information for this report was provided by AP.