The Obama administration moved a step closer Thursday toward approving a rule that would authorize 30-year permits enabling energy companies with wind farms to kill eagles without penalty.

The permits would cover what are known as eagle "takings," in which bird deaths are associated with an activity but are not the purpose of it. The Office of Management and Budget completed its review of the rule Thursday.

The Interior Department argued that the longer permit period "will provide a measure of certainty to project proponents and their funders, while continuing to protect eagles consistent with statutory mandates." Permits currently last for five years.

The agency said the permits would facilitate more renewable energy projects. But environmental groups have hotly contested the proposal, saying it lets energy companies off the hook too easily for killing eagles.

The action comes after Duke Energy paid $1 million in a settlement with the Justice Department over eagle and other bird deaths at a pair of Wyoming wind power sites.

On top of that, a federal study released in September found that wind farms killed at least 85 golden and bald eagles between 1997 and 2012.

But wind turbines are not a major source of such deaths, argued the American Wind Energy Association, the industry's main lobbying organization. It said wind farms are responsible for 2 percent of all human-caused eagle fatalities.