Oil impacts Redfish Bay in Louisiana's birdsfoot delta, where the Mississippi River empties into the Gulf of Mexico, May 27, 2010. BP said on Friday it may need two more days to know if its complex maneuver to plug a gushing Gulf of Mexico oil well has worked, while President Barack Obama warned there was no "silver bullet" solution to the biggest oil spill in U.S. history. Picture taken May 27, 2010. REUTERS/Jeffrey Dubinsky/Gulf Restoration Network (UNITED STATES - Tags: DISASTER ENVIRONMENT ENERGY)