For all its downsides, the budget stalemate has helped shed light on a pressing question -- which parts of the government can Americans live without?

The partial government shutdown effectively has forced every agency in Washington to answer that question. Ahead of the budget deadline, agency heads were ordered to figure out how many employees would be deemed "essential" in case of a partial shutdown.

The results (which can be viewed here) give a glimpse into how important, or not, dozens of federal agencies and departments are to Americans' everyday lives.

At the bottom of the list happen to be popular targets for Republicans, whom Democrats are aggressively blaming for the current standoff.

The Environmental Protection Agency, for instance, has retained just 6.6 percent of its workforce. Of more than 16,000 employees, just over 1,000 are on the job.

The Internal Revenue Service, which has taken a beating this year over allegations that it targeted conservative groups for additional scrutiny, has just 9.3 percent of its workforce hanging around this week. At a big agency like the IRS, that's still nearly 9,000 workers.

Even NASA, the storied beacon of space exploration which has helped define the direction of this country, is down to 3 percent of its staff.

"Government doesn't do a great job of measuring things like efficiency and productivity of its workforce," said Tom Shoop, editor in chief of GovExec.com, in explaining the apparent excess staff. "There's also the factor that as the budget deficit grows bigger, there's just a growing sense that government is very big and a lot of people question whether they're getting what they're paying for."

For the most part, employees who are considered "excepted" -- a technical term that is slightly less offensive for furloughed workers than "essential" -- are those considered to be engaged in the protection of life and property and other important tasks. It also includes those whose paychecks are covered by something other than Congress' annual budget bills.

So which agencies are most "essential?" Mostly, those dealing with public safety and security -- and veterans.

The Department of Veterans Affairs is at the top of the list of agencies that are operating at nearly full force. According to the contingency plans, the department has 95 percent of its workers on the job. Signaling the political importance of keeping that agency running, House Republican lawmakers are pushing a bill Thursday to make sure all VA operations are funded.

Following close behind the VA is the Department of Homeland Security, which is responsible for everything from airport security to Border Patrol to the Secret Service. Eighty-six percent of staffers are at work for the DHS during the budget stalemate. The Justice Department has nearly as many.

In all, about 800,000 federal workers are expected to face furlough during the impasse. Those employees were sent home this week, forbidden from working until a deal is reached.

Those decisions were the result of long-standing contingency plans.

"Each agency has to put together a plan that they ... submit to (the White House Office of Management and Budget), identifying which employees they have who they believe are essential for the safety of life and the protection of property," Charles Konigsberg, former assistant OMB director, said.

For the most part, federal agencies have furloughed the majority of their workforce.

At the Department of Commerce, agency heads determined 13 percent of the staff would stay on during a partial shutdown. At the Department of Education and the Department of Housing and Urban Development, only a few hundred workers were at the office this week -- representing well under 10 percent of each department.

Fox News' James Rosen contributed to this report.