The freeze will keep the grey wolf on the endangered species list for now, and will halt a rule that would have made it easier for industrial plants and refineries to expand without having to apply for new federal pollution permits.
"It is important that President Obama's appointees and designees have the opportunity to review and approve any new or pending regulations," White House Chief of Staff Rahm Emanuel said in a memo sent Tuesday evening to all federal departments and agencies.
But the order won't affect other last-minute Bush administration environmental rules, including those that open some Western lands to oil shale development, allow federal agencies to bypass talking to outside experts when deciding whether proposed projects will harm endangered species, and eliminate requirements that factory farms report air pollution from animal waste.
"Unfortunately the list of harmful rules not being affected outnumbers the rules that will be blocked by this Obama administration memo," said John Walke of the National Resources Defense Council.
That's because the Obama administration order can only block rules that are still pending. Federal regulations become final either 30 days -- for so-called "insignificant" rules -- or 60 days -- for more major regulation changes -- after they are published.
The Bush administration's rules that are unaffected by the order were those issued by the end of November and became final before Obama took office Jan. 20.
Once a rule is final, it can only be changed through the process of making a new rule, through legal challenges, or through congressional action.
Both the Bush administration and Obama administration's actions have followed a well-known script. Every president since Ronald Reagan has, on his first day in office, issued a memo to block all of the previous administration's pending rules, according to the Washington Post.
And most administrations, especially those ceding power to the other party, have pushed through more regulations than usual in their final days -- so-called "midnight rules."
"During transition periods, there's a spike in regulatory output," said Reece Rushing, director of regulatory policy at the Center for American Progress.
Rushing said that the main difference between the Obama administration's memo and past memos is that Obama also asked agencies to consider delaying by 60 days the effective date of rule changes that have been finalized, but have not yet gone into effect. Obama also asked the agencies to provide reasons for any delay.
In 2001, the Bush administration also asked agencies to delay the effective dates of new rules, but because the rules were postponed without reasons, many of the delays were challenged in court.