Mr Grassley said senators who feel sorry about the past war in Vietnam are expected to vote for the agreement, but there are some obstacles in Congress.

As part of the agreement, the US Congress will likely to grant the permanent normal trade relations (PNTR) status for Vietnam. Whether or not the US Senate votes for the agreement before the US Congressional holiday in August depends on the number of amendments proposed by Senators, said Mr Grassley.

Meanwhile, many US businesses expressed hope that the PNTR legislation will be passed by the US Congress before August.  

The White House wants the US Congress to approve the agreement before President George W. Bush attends the Asia-Pacific Economic Co-operation (APEC) summit in Hanoi this November.