MONTEVIDEO, Uruguay - President Bush asked Congress on Saturday for $3.2 billion to pay for 8,200 more U.S. troops needed in Afghanistan and Iraq on top of the 21,500-troop buildup he announced in January.

Iraqi soldiers examine the site of a car bomb attack that killed 20 and wounded 25 at a checkpoint into the Shiite enclave of Baghdad, Iraq, Saturday, March 10, 2007. [AP]

Bush wants Congress to fund 3,500 new U.S. troops to expand training of local police and army units in Afghanistan. The money also would pay for the estimated 3,500 existing U.S. troops he already announced would be staying longer in the region to counter an anticipated Taliban offensive in Afghanistan this spring.

In Iraq, most of the additional troops would help with the latest Baghdad security plan, which is getting under way in the capital. The money would pay for 2,400 combat support troops, 2,200 military police forces and 129 troops for reconstruction teams.

The budget revisions come as many lawmakers opposed to the buildup in Iraq are debating funding for the war. But in a letter to House Speaker Nancy Pelosi (news, bio, voting record), Bush proposed canceling $3.2 billion in low-priority defense items to offset the extra money needed to support the additional troops.

Cutting the programs, he said, would eliminate the need to increase the overall $93.4 billion in additional defense money he's already requested to finance this year's war operations in Iraq and Afghanistan.

"This revised request would better align resources based on the assessment of military commanders to achieve the goal of establishing Iraq and Afghanistan as democratic and secure nations that are free of terrorism," Bush wrote in his letter to lawmakers.

Bush signed the letter on his flight Friday from Brazil to Uruguay, part of his five-nation tour of Latin America that continues on Sunday in Colombia. The White House released the letter Saturday in Montevideo, Uruguay.

Gen. David Petraeus, the top U.S. commander in Iraq, recently hinted of the need to bolster the U.S. troop presence in Iraq.

"Gen. Petraeus expects under the Baghdad security plan as well as other parts of Iraq, that the number of people going into detention will increase and so these military police forces will be for that," said Gordon Johndroe, a spokesman for the National Security Council.