The two countries recently signed an accord to work on development of space technology and satellites.
But officials warned that they might not reach agreement in time for world leaders to sign accords Friday.
Brazil signed a $41.5 billion accord with international lenders in November 1998.
Officials expressed hope that the two adversaries will sign accords.
Japan and China have just signed an accord promising to reduce barriers to trade.
Both sides came to the talks in Sapoa with strong reasons to sign an accord.
Mr. Bush is expected to sign an accord on scientific cooperation.
Representatives of 58 countries signed a nonbinding accord not to use children under 18 in wars.
Argentina wanted the leaders to agree to sign an accord by 2000 that would set up a trade zone by 2015.
In 1984 it signed an accord with the state parks agency - which oversees government work on historic buildings.