The U.S. Senate has gone on a five-week vacation without renewing the operating authority of the Federal Aviation Administration.

The agency that oversees the nation's airlines and air traffic partially shut down on July 23 and may not return to full operation for at least another month.

President Barack Obama made a last-minute appeal Tuesday, demanding the Senate take action before recessing. He called the congressional stalemate over the FAA another Washington-inflicted wound on America. He also said failure to approve the renewal has stalled airport construction projects at a cost of tens of thousands of jobs.

As of now, the FAA cannot collect federal taxes on airline tickets which could cost the government more than $1 billion. About 4,000 FAA employees have been laid off.

The Republican-controlled House of Representatives passed an FAA bill before it recessed. But Senate Democrats object to a provision in the House bill eliminating subsidies for air service in small towns and rural communities.

U.S. Transportation Secretary Ray LaHood promises that air traffic controllers will stay on the job and that the congressional impasse will not put passenger safety at risk.