House Speaker Mike Johnson of Louisiana is being pushed by far-right Republicans to abandon the debt limit deal the party struck with the White House. House Television via AP

Congress is careening toward another government shutdown deadline.

Without new government funding legislation, crucial services and legions of federal workers will be sidelined, or go unpaid, as soon as midnight late Friday. Another larger shutdown deadline waits just a week later.

Here’s what you need to know about what Congress is – or isn’t – doing to prevent a shutdown.

WHAT IS A GOVERNMENT SHUTDOWN?

The federal government can only spend money that’s appropriated by Congress – that is, spelled out in a funding law. When those laws expire, Congress has to approve new funding or agencies have to shut down. That’s what lawmakers are facing down this week: Congress approved funding legislation for parts of the government that is set to expire at 12:01 a.m. Saturday.

WHICH PARTS OF THE GOVERNMENT WOULD SHUT DOWN?

The funding that expires Saturday covers a number of agencies that represent roughly 20 percent of the federal government:

• Department of Housing and Urban Development

• Department of Transportation

• Department of Veterans Affairs

• Department of Energy

• Department of Agriculture

• Food and Drug Administration

Some portions of the Defense Department, such as the Army Corps of Engineers, and the Interior Department are also covered by the expiring funds.

Not all of the agencies and departments whose funding will run out would see the same effects – and most wouldn’t shutter completely. Activities that are considered essential to public safety, economic stability and the president’s constitutional authority continue during a shutdown. For example, air traffic controllers would stay on the job, but go unpaid, as would food safety inspectors at the FDA.

At the Department of Veterans Affairs, veterans’ benefits, including health care and pensions, would continue during a government shutdown, according to the department’s contingency plan. Ninety-six percent of the agency’s nearly 414,000 employees would continue working, either because their pay doesn’t depend on annual appropriations or because they are exempt from furloughs.

WHO WOULD BE AFFECTED?

A partial government shutdown would affect a wide range of crucial federal services and thousands of employees.

Programs like SNAP (Supplemental Nutritional Assistance Program) or WIC (Special Supplemental Nutrition Program for Women, Infants, and Children) would continue without interruption – for a time. Both have contingency funds that can carry over past the deadline. But that funding only lasts so long. Officials have said if a shutdown drags on or if WIC goes unfunded, it will have to begin wait-listing participants.

Some of the roughly 5 million families who receive rental assistance from the U.S. government could see sharp cuts to their benefits – and even the threat of eviction – unless lawmakers fully fund key housing programs.

Most government employees who are crucial to travel safety would continue working without pay during a government shutdown, but that designation varies by agency. Government scientists at the Agriculture Department would stop tracing and studying animal-borne diseases, for example.

But at the Federal Aviation Administration, the agency responsible for air traffic controllers and aircraft and pilot safety certifications, most employees would continue their work. Some 16,000 of its more than 45,000 employees would be furloughed, the agency projects, but air traffic controllers, accident investigators, anti-terrorism and intelligence officials and other safety officials would stay on the job.

WHEN WOULD IT BEGIN?

Federal funding expires on Friday, March 1, so a shutdown would begin at 12:01 a.m. March 2.

Funding for the remaining 80 percent of the federal government, including the departments of Defense, Homeland Security and State, expires on March 8; that larger partial shutdown would begin at 12:01 a.m. on March 9.

WHY IS THIS HAPPENING AGAIN?

This impending shutdown can trace its roots back to the spring of 2023. President Biden and then-House Speaker Kevin McCarthy, R-Calif., made an agreement to hold down federal discretionary spending in the 2024 fiscal year – the current one, which began Oct. 1 – in exchange for suspending the U.S. debt limit.

That set off a brawl within the House Republican conference. Far-right lawmakers were furious with McCarthy for not extracting deeper spending cuts. When Congress sat at the precipice of a government shutdown in September, those members wanted McCarthy to buck the debt limit arrangement and negotiate for more cuts. McCarthy refused and passed a stopgap funding bill, known as a continuing resolution or CR, with the help of Democratic votes. A band of Republican rebels, led by Rep. Matt Gaetz, R-Fla., ousted him from the speakership in retaliation in early October. McCarthy resigned from Congress in December.

Republicans elected Rep. Mike Johnson, R-La., to replace McCarthy as speaker, but Johnson hasn’t fared much better in taming the Republican conference or securing spending cuts. Under Johnson’s leadership, Congress passed another CR in November, then another in January with staggered deadlines.

Now the first part of that most recent funding bill is about to expire, and far-right Republicans have pushed Johnson, as they pushed McCarthy, to abandon the debt limit deal. Johnson, like McCarthy, refused. But he promised GOP lawmakers that he’d secure conservative policy provisions – on issues ranging from restricting abortion access, limiting LGBTQ rights, promoting fossil fuels and more – in the funding bills, essentially trying to roll back vast swaths of Biden’s legislative achievements and executive actions.

But Johnson, who enjoys only a two-seat majority in the House, doesn’t have much leverage in negotiations with the Democratic-controlled Senate or White House, so winning those policy debates has proved difficult, pushing negotiators up against Saturday’s shutdown deadline.

WHAT ARE THE NEXT STEPS?

Members of Congress say they will negotiate up until the last minute before a shutdown, but time is running low. They have four options to keep the government open, or minimize a shutdown’s effects:

Pass the bills: Lawmakers could drop their disagreements and speedily adopt legislation to fund the government. There’s been positive movement in that direction since Biden summoned congressional leaders to the White House on Tuesday, but an agreement is still a ways off.

Pass another CR: Congress could drop its plan to pass appropriations – or annual spending bills – and pass another CR, in essence kicking the can down the road again. Lawmakers are already considering a continuing resolution to avoid the March 9 shutdown deadline, which would extend funding for the agencies affected until March 22.

Pass a very short CR: If lawmakers are nearing an agreement but just need another beat to dot their i’s and cross their t’s, they could pass a CR that lasts only a few days. That would keep the government open and give both the House and Senate enough time to take up new spending legislation without an intense time crunch. Senate Republicans discussed this option at their weekly lunch meeting on Tuesday; it’s unclear how House Republicans would feel about this approach.

Shut down the government, but keep it brief: Congress actually buys itself a little a more time to solve government shutdowns each time it passes a CR. It’s been setting the deadline on a Friday, so if the government does shut down, lawmakers have the weekend to try to open the government up again while most federal workers are already off the clock. If lawmakers are very close to a deal, they could choose to try to pass legislation to resolve the situation over the weekend and have the government open again on Monday like nothing ever happened. In this scenario, a partial shutdown might only last a few hours, even if final passage of new funding legislation comes Saturday morning.

Tony Romm contributed to this report.