The Obama administration is increasing pressure on the Iraqi government to open its oilfields to foreign companies and thwart a referendum on an early US withdrawal. In meetings with Iraqi officials Wednesday, Vice President Joe Biden reportedly expressed his opposition to a national referendum on whether to approve the US-Iraqi Status of Forces Agreement, or SOFA. The agreement calls for a US withdrawal by the end of 2011. But if Iraqis reject the timetable, US troops would be forced to leave nearly one year earlier. The Washington Post reports Biden also pressed Iraqi leaders on altering oil laws to allow more foreign investment.