Fresh waves of crude oil swept onto Gulf of Mexico shores Tuesday as energy giant BP readied for a desperate effort to plug a massive leak that is threatening an environmental disaster. With the political fallout from the leak mounting, BP engineers laid plans to stifle the leak using a method known as a 'top kill' that would see heavy drilling fluids, then cement, injected into the well. The British oil firm's chief operating officer Doug Suttles said the already- delayed operation would now take place Wednesday. He told CNN that the bid, using robotic submarines on the seabed, had a six or seven out of 10 chance of working. If the 'top kill' effort fails, relief wells to divert the flow and allow the leaking well to be sealed will not be ready until August at the earliest, meaning tens of millions more barrels of crude could stream into the Gulf. BP's chief executive Tony Hayward admitted Monday he was 'gutted' that oil was now starting to clog fragile Louisiana wetlands, as footage emerged of helpless sea birds slimed by a tide of thick crude. The slick was spawned by an explosion on a BP-leased Deepwater Horizon rig on April 20, which killed 11 workers. US Interior Secretary Ken Salazar meanwhile betrayed simmering frustration inside President Barack Obama's administration when he branded the disaster 'a BP mess, a horrible mess, a massive environmental mess,' during a trip to Louisiana. Salazar had Sunday threatened to push BP 'out of the way' if it could not stop the leak, but Obama's pointman on the disaster admitted the government had few options. Coast Guard chief Thad Allen, speaking to reporters at the White House, said rebuffing BP may not work since the US government lacked the expertise and equipment needed to stop the leak 5,000 feet (1,500 meters) under water. 'To push BP out of the way would raise a question -- to replace them with what?' Allen said, revealing that he had consulted another major oil firm on the situation, and been satisfied BP was doing everything that could be done. 'They're exhausting every technical means possible to deal with that leak,' he insisted. Allen also said he was frequently communicating directly on the phone with Hayward. White House spokesman Robert Gibbs said Obama would take questions from the media on Thursday after getting a report from Salazar on whether the disaster impacted his plans to expand offshore drilling. And at BP, 'they have every impetus... to try to seal off this leak and they're working hard to do it. And we're working with them,' senior White House advisor David Axelrod told CNN. 'All the scientists within our government are a part of their strategic team in dealing with this. The Coast Guard has been on the scene from the beginning,' Axelrod said. Over a month after the accident, Obama's opponents have begun to take swings at the White House and local politicians have complained requests for resources have not yet been met. Louisiana Governor Bobby Jindal, a Republican, pleaded for sand barriers to be built to protect the coast, and told grim tales of birds unable to fly because their feathers were fused together by oil. Jindal wants to use dredgers to create barrier islands between the encroaching oil and wetlands, but the federal government is still studying whether the idea would work. BP has also intensified its PR offensive, taking out ads in major US newspapers and pledging up to 500 million dollars to study the impact of the spill. 'I think this is clearly a major reputational issue for BP,' Hayward said in Port Fourchon in southern Louisiana, contradicting earlier statements in which he said the environmental impact would be 'very, very modest.' 'It's clear that the defense of the shoreline, at this point, has not been successful,' Hayward said. 'I feel devastated by that, absolutely gutted. What I can tell you is that we are here for the long haul. We are going to clean every drop of oil off the shore.' 