US President Barack Obama headed to the Gulf Coast on Sunday for a firsthand update on a massive and growing oil slick creeping toward American US shores from Louisiana to Florida. Crews have had little success stemming the flow from the ruptured well on the sea floor off Louisiana or removing oil from the surface by skimming it, burning it or dispersing it with chemicals. Adding to the gloomy outlook were warnings from experts that an uncontrolled gusher could create a nightmare scenario if the Gulf Stream current carries it toward the Atlantic. There is growing criticism that the government and oil company BP PLC should have done more to stave off the disaster, which cast a pall over the region's economy and fragile environment. Moving to blunt criticism that the Obama administration has been slow in reacting to the largest US crude oil spill in decades, the White House dispatched two Cabinet members to make the rounds of the Sunday television talk shows. As the spill surged toward disastrous proportions, critical questions lingered: Who created the conditions that caused the gusher? Did BP and the government react robustly enough in its early days? And, most important, how can it be stopped before the damage gets worse? The April 20 explosion of the Deepwater Horizon exploration rig killed 11 workers and the subsequent flow of oil threatens beaches, fragile marshes and marine mammals, along with fishing grounds that are among the world's most productive. The Coast Guard conceded Saturday that it's nearly impossible to know how much oil has gushed since the blast, after saying earlier it was at least 1.6 million gallons (6 million liters) - equivalent to about 2½ Olympic-sized swimming pools. Even at that rate, the spill should eclipse the 1989 Exxon Valdez incident as the worst US oil disaster in history in a matter of weeks. But a growing number of experts warned that the situation may already be much worse. The oil slick over the water's surface appeared to triple in size over the past two days, which could indicate an increase in the rate that oil is spewing from the well, according to one analysis of images collected from satellites and reviewed by the University of Miami.
