US Democratic Sen. Barack Obama and Republican Sen. Sam Brownback are pressuring US companies to stop investing in Iran's oil and gas industries. The two presidential candidates have introduced a measure encouraging divestment from companies that do business with Iran. The bill would authorize state and local governments to divest their assets from such companies and give legal protection to people who divest. It would also require the federal government to publish a list of companies investing at least $20 million (â‚¬14.84 million) in Iran's oil and gas industries. "The Iranian regime is the world's biggest state sponsor of terror, proudly flaunts an illegal nuclear program and continues to violate the basic human rights of the Iranian people," Brownback said Friday.