The US Senate is expected to vote before the end of September - possibly as soon as this week - on legislation giving the US Department of Agriculture authority to shut down a meat or poultry processor who fails consistently to meet the government's standards for pathogens such as Salmonella. The proposal has been introduced by US Senator Tom Harkin, an Iowa Democrat who chairs the Senate Agriculture Committee. His chief of staff said Harkin would likely offer the language as an amendment to the annual bill appropriating money for USDA.