Illustration by Janet Loehrke, USA TODAY

The federal government will likely shut down Oct. 1 after President Donald Trump and congressional leaders failed to reach a funding compromise and adjourned at 8:24 p.m. on Sept. 30. The partial shutdown will likely start at midnight.

Senators rejected two deals, one from Democrats, the other from Republicans, that would have prevented the shutdown. The Republican plan, which would have kept the government open until Nov. 21, failed on a 55 to 45 vote, USA TODAY reported. At least 60 votes are needed to pass.

The federal government will run out of money at the end of the fiscal year, unless members of Congress overcome partisan differences and agree to pass a funding bill.

The federal government has closed down 21 times, with a total of 161 days since 1976. The pending shutdown primarily concerns health care spending.

Democrats want to prevent Obamacare subsidies from lapsing and reverse cuts to Medicaid funding enacted by Trump's tax and spend law, known as the Big Beautiful Bill.

When have government shutdowns taken place?

Government shutdowns have taken place during seven presidencies. President Jimmy Carter has the most days, 56, from 1977 to 1979. Trump has the longest consecutive stretch of days, 34, in 2019.

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That's an average of nearly eight days per shutdown. Three shutdowns took place during Trump's first term in office, but one of them lasted only a few hours.

What happens during a government shutdown?

Like any home or business, the federal government must pay its bills. When Congress can’t agree on how to appropriate money for funding, non-essential departments of the government shut down. Funding expires Sept. 30.

In past shutdowns, hundreds of thousands of federal workers, those deemed nonessential, have been furloughed or sent home without pay. They were reimbursed when they returned.

However, the Office of Management and Budget has instructed federal agencies to prepare for mass layoffs, not just temporary furloughs.

Employees who are classified as essential for critical operations in defense, energy, agriculture, and other sectors would continue to work, but without pay. They are reimbursed when the shutdown ends.

Where federal employees work

Which presidents have had the longest government shutdowns?

Longest single shutdown: A review shows the longest shutdown, 34 days in a row, took place under Trump, starting in December 2018 and ending Jan. 25, 2019.

Highest number of shutdown days: The president with the most is Jimmy Carter, who had 56 days in five separate shutdowns from 1977 to 1979. Second is Trump, with 36 days in two shutdowns in 2018 and 2019. Bill Clinton is third with 26 days in two shutdowns in 1995 and 1996.

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Who keeps working during a government shutdown?

Though the OMB has told departments and agencies to prepare for mass layoffs, not just temporary furloughs, staffers at essential agencies would continue to work if the shutdown happens, including:

Defense: Branches of the U.S. military and the Coast Guard would remain on duty.

Law enforcement and protection: The Secret Service, FBI, Drug Enforcement Administration, and others would not be affected.

Border security: Most Border Patrol officers, Immigration and Customs Enforcement agents, and customs officials would keep working.

Prisons: Officers would stay on the job.

Travel: Transportation Security Administration agents at airports and air-traffic controllers would be required to work.

Mail: The U.S. Postal Service would remain open.

Taxes: The IRS would keep working.

Nearly 50,000 Coast Guard employees went without pay for 35 days during a 2019 shutdown, NPR reported. During peacetime, the Coast Guard is the only military branch under the Department of Homeland Security.

CONTRIBUTING Joey Garrison, Iris Seaton, Terry Moseley, Olivia Munson, Riley Beggin, Sudiksha Kochi, Eric Lagatta, Savannah Kuchar, Fernando Cervantes Jr., Jim Sergent, USA TODAY

SOURCE USA TODAY Network reporting and research; Reuters

This article originally appeared on USA TODAY: Government shutdowns, what's happened in past is likely to happen now

Reporting by George Petras and Ramon Padilla, USA TODAY / USA TODAY

USA TODAY Network via Reuters Connect