Landrieu, a Democrat, said she will object to a vote on Jacob Lew to head the Office of Management and Budget until the administration lifts or significantly modifies the moratorium imposed last May after the BP oil spill.
"I cannot support further action on Mr. Lew's nomination to be a key economic advisor to the president until I am convinced that the president and his administration understand the detrimental impacts that the actual and de facto moratoria continue to have on the Gulf Coast," she said in a letter to Senate Majority Leader Harry Reid.
Lew, who also served as OMB chief during the Clinton administration, was approved by the Senate Budget Committee Thursday on a 22-1 vote and appeared headed for easy confirmation by the full Senate. President Barack Obama nominated him in July after former OMB director Peter Orszag resigned.
But under Senate rules, one senator can object to a nominee or a bill advancing to the Senate floor. It takes 60 votes to overcome such an objection.
Landrieu has been a vocal critic of the moratorium, saying it is costing the Gulf Coast tens of thousands of jobs.
A federal report released at a Senate hearing last week said the moratorium likely caused a temporary loss of 8,000 to 12,000 jobs in the Gulf region, including about 2,000 on deepwater rigs.
Landrieu said that while Lew "clearly possesses the expertise necessary to serve as one of the president's most important economic advisors, I found that he lacked sufficient concern for the host of economic challenges confronting the Gulf Coast."