Green Day's 2005 hit "Wake me up, when September ends" may see a revival among federal workers at the Food and Drug Administration and the National Institutes of Health and other agencies if President Donald Trump continues to ramp up his rhetoric about shutting down the government at the end of next month.

September is always a brutal month in Washington, and 2017 is not expected to be any different.

Congress, which returns from its August recess next week, has until Sept. 30 to pass a new spending bill. If it fails to do so — or Trump vetoes it — the government will be forced to furlough most of its workforce and shut down its non-essential services.

The last time the federal government shutdown, in October 2013 — a stint that lasted 16 days — the U.S. economy lost $24 billion, according to S&P Global Ratings, and the federal government was out $2 billion, the White House Office of Management and Budget estimated.

Even preparing for a shutdown — whether one occurs or not — can result in the loss of productivity, because federal agencies are consumed with the planning work involved, according to an October 2014 report from the Government Accountability Office, or GAO.

During the 2013 shutdown, the NIH was forced to furlough 15,712 employees, or about 80% of its workforce, including scientists involved in critical research, the GAO reported. The NIH's Clinical Center had to turn away hundreds of patients, whose treatments were put on hold, unless they were in a life-threatening situation. The agency's grants management activities also effectively ceased, resulting in the review process for over 13,700 applications having to be rescheduled.

At the FDA, where about 45% of its personnel were furloughed, a lack of security at the agency's Center for Biologics Evaluation and Research left its systems unprotected, resulting in a cyber attack in which 14,000 company accounts were hacked, according to an August 2015 congressional report.

The shutdown in 2013 occurred because Republicans tried to tie the fiscal year 2014 funding package to their fight over repealing the Affordable Care Act — a law they still have not succeeded in dismantling.

At issue for Congress in getting the fiscal year 2018 funding across the finish line is Trump's border wall between the U.S. and Mexico, the costs for which he is now demanding American taxpayers cover, despite his campaign promises to get the nation to the south to pay for it.

Trump has said he will somehow get Mexico to later reimburse the U.S. for building the wall — the estimated costs for which have ranged from $4 billion to $70 billion — although he has not provided any details.

"Believe me, if we have to close down our government, we're building that wall," Trump declared during an Aug. 22 speech in Phoenix.

But House Speaker Paul Ryan, R-Wis., dismissed Trump's threat, telling reporters the next day a government shutdown is not what most Americans or lawmakers on Capitol Hill want to see happen.

"I don't think anyone's interested in having a shutdown," Ryan said.

But Neil Bradley, senior vice president and chief policy officer at the U.S. Chamber of Commerce, said concern about a potential government shutdown was growing.

"I'm not prepared to say it's likely at the moment, but I think it's right we should be concerned about it and thinking about it," Bradley said during an Aug. 27 appearance on C-SPAN's "Newsmakers."

He said his organization has been emphasizing the consequences of a government shutdown — urging businesses to get their permits in order immediately and advising anyone planning to travel abroad to obtain their visas right away.

Bradley anticipated Americans would have a clearer view on the situation in a few weeks.

"I think we have to see how September plays out," he said. "These things usually have highs and lows and the rhetoric will ramp up."

While Bradley said "no one is hitting the panic button yet" over a possible government shutdown on Oct. 1, he said his organization is reminding policymakers now that "nothing really good" comes out of such a situation.

Bradley also had a warning for Trump, who had previously threatened a government shutdown in May.

"My experience has been whoever tries to hold government funding hostage to get something, it's usually not a strategy that has historically worked out very well," Bradley said.

Senate health leaders eye moderation in healthcare

Before September ends, lawmakers are also hoping to get some bipartisan legislation passed aimed at stabilizing healthcare insurance premiums and improving affordability and accessibility for individuals purchasing coverage.

Senate Health, Education, Labor and Pensions, or HELP, Committee leaders Sens. Lamar Alexander, R-Tenn., and Patty Murray, D-Wash., the chairman and ranking member, respectively, have acknowledged it is unlikely Congress will pass a comprehensive bipartisan healthcare reform bill anytime soon.

So the HELP Committee chiefs have set their sights on more moderate fixes, like funding the so-called cost-sharing reduction payments and improving the ACA's 1332 waivers — actions the two senators said they think are doable.

The cost-sharing payments help cover deductibles and copayments for about 7 million low-income Americans enrolled in ACA plans offered by private insurers through the government-run marketplace.

The 1332 waivers permit states to make changes to insurance plans and manage their health systems independent of the federal government.

Alexander and Murray have invited a group of five moderate governors from both parties to testify Sept. 7 before their panel: Charlie Baker, R-Mass.; Steve Bullock, D-Mont.; Bill Haslam, R-Tenn.; Gary Herbert, R-Utah; and John Hickenlooper, D-Colo.

A day earlier, the committee will hear from five state insurance commissioners: Lori Wing-Heier of Alaska; Theresa Miller of Pennsylvania; John Doak of Oklahoma; Julie Mix McPeak of Tennessee; and Mike Kreidler of Washington.

Trump slow to make opioid declaration official

Meanwhile, August is almost over, but Trump has yet to make his declaration official that the opioid crisis in the U.S. is a national emergency.

A White House commission said in a July 31 report that the nation's opioid epidemic had reached the point of needing an emergency declaration, which would ensure that more federal funding was funneled toward addressing the situation.

The panel, led by Republican New Jersey Gov. Chris Christie, urged Trump to take action to declare the crisis a national emergency.

"The opioid crisis is an emergency, and I'm saying officially right now, it is an emergency," Trump told reporters Aug. 10 from his New Jersey golf club, where he was vacationing.

Trump received praise for taking such a stand.

But he has yet to complete the legal paperwork declaring the epidemic a national emergency.

"The president recently instructed his administration to take all appropriate and emergency measures to confront the opioid crisis," a White House spokesman told S&P Global Market Intelligence in an emailed response to questions. "Right now these actions are undergoing a legal review."

He provided no other details about the review, including a timeline for its completion.

S&P Global Ratings and S&P Global Market Intelligence are owned by S&P Global Inc.