The threat of a government shutdown goes on as the divided US Congress haggles over a new budget.
Travelers could get caught in the partisan crosshairs as early as Tuesday, October 1, the beginning of the federal fiscal year.
More than a third of federal workers would be told to stay home if Congress fails to approve a temporary spending bill to keep the government running.
That would force the closure of national parks, all 19 Smithsonian museums in Washington, and US consulates around the world.
Details about shutdown plans for each agency will be posted on the OMB and individual agency websites by Friday afternoon. Formal furlough notices would be sent on Tuesday.
"Fifty percent of our members may be locked out of work altogether during this shutdown," said J. David Cox Sr., president of the American Federation of Government Employees.
The last shutdown, in 1995, lasted three weeks.
During that period, more than 200,000 U.S. applications for passports and 20,000 visa applications by prospective visitors went unprocessed each day.
