What's the worst that could happen?

If Congress can't come up with a way to continue funding the federal government by Oct. 1, some experts say many people won't notice much, at least right away.

But after a few days, many more will. So, what's the worst-case scenario for a shutdown?

Imagine the National Institutes of Health not being able to admit new patients, important IT contracts stalled and up to 800,000 employees furloughed with Congress electing not to provide back pay, said John Palguta, a former federal executive and now vice president of policy at the Partnership for Public Service.

Then imagine it lasting a few weeks or longer.

Palguta and his wife, both former feds – he at the Merit Systems Protection Board and she at the Commerce Department – were furloughed in a 21-day shutdown in 1996.

Federal IT systems are larger, more complex and require significantly more manpower than they did in the 1990s – even small security or accessibility issues could be magnified greatly during a shutdown of any significant duration.

"A shutdown is just a horrible way to run government and bad things happen, but the worst-case scenario is a shutdown takes place over any significant length of time," Palguta said. "The pressure would be immense after a few days."

Personnel and programs necessary for critical services are supposed to be exempt from furloughs or cancelation per federal law, and OMB has issued guidance to agencies in the midst of planning for a potential shutdown. Yet Palguta said furloughing employees or canceling programs or contracts deemed "non-essential" is likely to lead to significant problems in a variety of areas where the government provides customer service, citing student loan processing as an example.

"It was nerve-wracking as an employee, when you don't know when you're coming back," Palguta said, noting that non-excepted feds could go out and get other jobs if necessary during a shutdown.

But the longer it goes, the worse it could be for average Americans who don't work for the government but depend on it for their economic well being.

"The worst-case scenario is that a shutdown lasts through the debt ceiling issue. A shutdown might be disastrous for the lives of many government contractors and federal employees, but a breach of the debt ceiling would have a national economic impact," said Kevin Plexico, vice president for information services at Deltek.

Contractors already faced the burden of dividing their last days of certainty between managing end-of-the-fiscal-year contracting options and deciding what IT contracts might be shut down, stopped or extended, according to Mark Forman, former administrator for e-government and IT at the Office of Management and Budget.

"The people supposed to be making all this work are the same people working on contingency plans in determining who stays on, what contractors are cut, and the capacity really isn't there in the procurement workforce," said Forman. "In a worst-case scenario, neither gets done well."

Cyber- and cloud-security isn't supposed to be at-risk during a shutdown, according to several high-ranking IT professionals interviewed by FCW, because those mission-critical federal network defenders are supposed to be exempt from furloughs as well. Yet as James Lewis, director and senior fellow of the Technology and Public Policy Program at the Center for Strategic and International Studies told FCW, every agency will make their own determinations about which employees to send home.

"It's every network for itself around here," Lewis said.