A federal moratorium that has protected millions of renters from eviction since late March expires Friday, leaving millions of people at risk even as the novel coronavirus continues to spread across the country.

The moratorium covers renters who live in homes with federally backed mortgages, which the Urban Institute estimates to be 12.3 million households, or about 30 percent of all renters nationwide. Once the moratorium lapses, landlords can give their delinquent tenants 30 days’ notice and then begin filing eviction paperwork in late August.

The expiration of the federal protection may come as state and local eviction bans are also starting to expire and enhanced federal unemployment benefits that kept many renters afloat are scheduled to end. That will put more pressure on renters already scraping by, housing advocates say.

“We are looking at an eviction cliff, and once we fall over it, it will be hard to climb back,” said David Dworkin, president of the National Housing Conference, a nonprofit that advocates for affordable housing.

With expectations growing that the recession triggered by the pandemic could be deeper and longer than many economists expected, housing advocates are pressing Congress to step in to prevent a significant rise in evictions this year.

The House passed legislation to create a $100 billion rental assistance fund. Last week, Sen. Kamala D. Harris (D-Calif.) unveiled a sweeping housing plan that would ban evictions and foreclosures for a year while giving tenants up to 18 months to pay back missed payments.

The emergency rental assistance program passed by the House would help renters at the lowest income levels for up to two years, said Diane Yentel, president and chief executive of the National Low Income Housing Coalition. The money could be delivered through state housing finance agencies, public housing agencies or other nonprofits, she said.

“States and localities are pretty adept at setting up emergency rental assistance programs,” said Yentel.

But so far, a coronavirus relief bill being crafted by Senate Republicans and the White House does not appear to incorporate either idea. The proposals have also drawn opposition from some landlords who say they could be cumbersome to implement.

“If the government feels that renters should have a moratorium, the government should pay for it,” said Stephen J. Lehrman, who owns several apartment buildings in Westchester County, N.Y., and has challenged a state moratorium in court. “Why is rent the only payment that is being singled out for cancellation?”

The problems facing renters will only get worse once enhanced unemployment benefits run out and people exhaust their savings, said Dworkin, a former Treasury Department senior adviser on housing finance during the Obama and Trump administrations. Once any moratorium ends, tenants could be asked to come up with months of unpaid rent they can’t afford, he said.

“I am troubled about August and I am terrified about September,” he said. “A rental moratorium kicks the can down the road.”

Landlords across the country are fighting to end some state and local moratoriums, which they say have encouraged tenants to take a “rent holiday” whether they need the relief or not. Some were written too broadly and don’t allow the eviction of tenants even if they have become a danger to other renters, they say.

“My tenants call me every day and tell me what is going on with their lives, and I work with them,” said Lehrman. But a small number of renters will try to take advantage of moratoriums, he said.

In California, the Apartment Association of Greater Los Angeles is suing to block a measure adopted by the Los Angeles City Council allowing residents to defer rent for a year and waiving interest and late fees.

“Without an end in sight or any sort of financial relief whatsoever being offered to the city’s housing providers, many will be forced into foreclosure,” said Daniel Yukelson, executive director of the association.

A spokesperson for the city’s mayor didn’t immediately return an email seeking comment.

Peggy Christensen realized her retirement dreams in 2017 when she purchased an eight-unit apartment building an hour and a half outside Los Angeles. But that dream has turned into a nightmare, Christensen said, as eviction courts throughout California remain closed during the pandemic. One of her tenants was already two months delinquent when the ban went into effect and has now stopped returning phone calls, she said.

“It is so frustrating to me because there is no end in sight,” said Christensen, a retired medical devices consultant.

It is not just about the money, said Christensen, who is a plaintiff in a lawsuit challenging a local eviction moratorium. Two of her other tenants have also struggled in recent months, including one affected by the pandemic. She was able to work out deals with them, including accepting some late payments, she said.

But the other delinquent tenant has also started creating disturbances that bother other residents. “When the ban kicked in, there was no reason for her to pay or control her behavior, so the situation escalated,” Christensen said.