As government shutdown approaches, agencies to tell workers that furloughs are coming

Government agencies will begin warning their workers Thursday morning that they are preparing for a government shutdown -- and that they might have to go without pay.

Lawmakers have until the end of the day Sept. 30 to reach a deal to fund the federal government. If Congress doesn't act, the government will shut down at 12:01 a.m. ET on Sunday -- a situation that appears increasingly likely.

On Wednesday, the Office of Management and Budget gave the agencies the official heads up of a looming shutdown, according to two officials.

The procedural moves came as the union for the United States Capitol Police warned its members that it believes the shutdown could last two to four weeks.

The union note tells personnel to await an email and mailed letter advising them of their work status.

The Capitol Police, which protect members of Congress, as well as other law enforcement agencies are considered "excepted" services and would still report to work during a shutdown. They would receive back pay once the spending deal is passed. Other federal employees are furloughed and sent home without pay.

All federal workers would receive back pay once the spending deal is passed, although union officials say it's not a good solution. In the last shutdown in 2018, many essential employees called in sick because they struggled to pay for child care, gas and other expenses to come to work.

Officials tell ABC News that all federal agencies will begin notifying employees in the coming days whether they are selected to be furloughed or "excepted" and required to report to work without pay.

As many as 4 million workers could lose pay as a result of a shutdown -- about half of whom are military troops and personnel.