WASHINGTON (AFP) ― The Obama administration warned U.S. federal agencies Monday to prepare for a possible government shutdown that could hobble the U.S. economy, as Congress wrangled over a fast-approaching budget deadline.

The current fiscal year ends Sept. 30 and Congress remains bitterly split over spending, in particular over President Barack Obama’s landmark health care law.

The Republican-led House of Representatives passed a bill last week that would prevent a shutdown at the price of defunding what has become known as “Obamacare.” 

The president has warned that this is a non-starter, and now the House and Senate are left with one week to thrash out a compromise.

Should they fail, several government agencies will close on Oct. 1, placing hundreds of thousands of non-essential staff on unpaid leave.

Agencies are finalizing contingency plans.

The Pentagon said some civilian employees would be ordered to stay home, and Congress would have to ensure retroactive pay for civilians required to come to work.

“Military personnel would be paid but maybe not on time,” Pentagon spokesman George Little said.

White House senior advisor Dan Pfeiffer sought to lay blame squarely on Republicans, some of whom he accused of caring “more about scoring political points on Obamacare than keeping the government open and our economy moving forward.

“This kind of up-to-the-final-hour brinksmanship is beyond irresponsible,” he said in an email to Obama supporters.

The White House’s Office of Management and Budget recently issued a memo on how agencies should plan for a “lapse in appropriations.”

The State Department also cautioned employees.

Undersecretary for Management Patrick Kennedy fired off an email warning that a lapse could mean “a number of employees may be temporarily furloughed.”

Under a similar threat in 2011, the administration said 800,000 of roughly 2.1 million federal employees and contractors would be affected.

The Democratic-led Senate is expected to amend the House’s stopgap bill, which funds government at current levels until December 15, by removing the clause defunding Obamacare.

Senate Majority Leader Harry Reid set up a test vote for the bill this Wednesday, insisting he would not let Republican “fanatics” hold the government “hostage to their demands.”

“We’re not going to bow to Tea Party anarchists who deny the mere fact that Obamacare is the law,” Reid said.

A handful of Senate Republicans led by upstart Senator Ted Cruz have pledged to try to block Reid, but by Monday their supporters were peeling away.

Senate Minority Leader Mitch McConnell will not support Cruz’s blocking tactic nor will number two Senate Republican John Cornyn, their offices said.

If Reid gets his way, and he is likely to, the chamber would send the stripped-down legislation back to the House. What Republican House leaders do with it is an open question.

Pfeiffer said he was looking to “reasonable congressional Republicans” to help avoid a government shutdown or worse, a default on U.S. debt, with Congress needing to increase the nation’s legal borrowing limit in coming weeks or face default.

Americans are firmly opposed to shutting down government, polls show, even over an unpopular health law.

A CNBC poll showed 59 percent oppose the idea, while 19 percent would support shutting down government rather than funding Obamacare.

The U.S. government has shut down several times since the mid-1970s, sometimes for as few as three days.

The last two shutdowns happened in November and December of 1995, the second lasting 21 days, when Democrat Bill Clinton was president.

The battle pitted Clinton against Republican House speaker Newt Gingrich, with the president ultimately vetoing a draft spending bill he considered too austere.

At the time, Republicans controlled both chambers of Congress.

“Republicans now are in a much weaker position than they were in 1995,” University of Oklahoma history professor Steve Gillon told AFP. “But they’re pursuing the same strategy.”

In 1995, essential services like military operations, air traffic control and border security were uninterrupted, but programs not considered essential were shut down.

Garbage piled up in Washington, and research at the National Institutes of Health ground to a halt.

One of the most visible effects was on tourism: all 368 National Park Service sites closed, as did Smithsonian museums, disappointing seven million tourists.

When the dust settled, Gingrich was largely blamed for the debacle ― though he argues that the compromise resolution led to four straight years of balanced budgets.