In his first appearance before a Congressional panel Thursday, embattled BP Chief Executive Tony Hayward is expected to apologize for the devastating oil spill in the Gulf of Mexico and outline the extent to which his company is going to plug the leak and clean up the environmental mess. At the same time, according to prepared testimony released Wednesday night, Hayward will say that it is still too early to assign fault for the spill that threatens the coast along the Gulf. "I understand people want a simple answer about why this happened and who is to blame," Hayward will testify. "The truth, however, is that this is a complex accident, caused by an unprecedented combination of failures. A number of companies are involved including BP, and it is simply too early to understand the cause. There is still extensive work to do." Hayward's appearance before the House Energy and Commerce Subcommittee on Oversight and Investigations is expected to draw intense interest from the public and lawmakers. Energy and Commerce Chairman Henry Waxman (D-Calif.) and oversight subcommittee Chairman Bart Stupak (D-Mich.) have been sharply critical of BP. In the remarks provided in advance to reporters, Hayward opens with a contrite tone, saying that the explosion and resulting spill "never should have happened — and I am deeply sorry that they did." Hayward will say he fully grasps "the terrible reality of the situation" and was "personally devastated" when he learned that 11 men died on the Deepwater Horizon rig. In the written testimony, the BP chairman also says that he has learned several lessons, including that the industry should improve its ability to address deep-sea accidents and needs better safety technology. Hayward also will say that the company has marshaled considerable resources to deal with the crisis. "Some of the best minds and deepest expertise are being brought to bear," his testimony says. "With the possible exception of the space program in the 1960's it is difficult to imagine the gathering of a larger, more technically proficient team in one place in peacetime." Hayward, however, also takes a lawyerly approach to the question of liability. He says that BP as the "responsible party" under the Oil Pollution Act will defray the costs of cleaning up the spill and paying for the environmental impact. But, he adds, "it is important to understand that this responsible party' designation is distinct from an assessment of legal liability for the action that led to the spill." "Investigations into the causes of the incident are ongoing and issues of liability will be sorted out separately when the facts are clear and all the evidence is available," he says. From the outset, the companies involved in the oil rig accident, including rig owner Transocean; the company in charge of cementing the well, Halliburton; and the manufacturer of the malfunctioning blowout preventer on the rig, Cameron, have all pointed fingers at each other as to who may have been culpable. Hayward has faced considerable criticism for his handling of the crisis, including making comments that some people considered insensitive, such as saying he wanted his life back. On Wednesday he met with President Barack Obama and announced that BP would set up a $20 billion compensation fund to pay out claims stemming from the spill.