Reuters: The massive, uncontrolled oil spill in the Gulf of Mexico is roiling President Barack Obama’s carefully laid plans to open up America’s coasts to drilling again, while rattling Congress to a point where the oil industry’s exploratory plans could face a big shake-up. U.S. politicians are now in no mood to consider plans to open up new areas for drilling but if the crisis drags on, it could also affect exploration in existing production areas, such as the Gulf. BP Plc’s ruptured …