More than two months after the Obama administration lifted its ban on drilling in the deep-water Gulf of Mexico, oil companies are still waiting for approval to drill the first new oil well there. Experts now expect the wait to continue until the second half of 2011, and perhaps into 2012.

The administration says it is simply trying to enforce new safety rules adopted in the wake of the April 20 explosion of the Deepwater Horizon drilling rig, which killed 11 workers and set off the worst offshore oil spill in U.S. history....