BP Plc aims to retrieve a failed blowout preventer atop its ruptured Macondo well in the Gulf of Mexico on Thursday, the top U.S. official overseeing the oil spill response said on Monday.

But first, the company hopes to fish out a 3,500-foot (1,066-meter) drillpipe believed to be hanging in the giant stack of pipes and valves to ease the removal and replacement with another blowout preventer.