Throughout the coronavirus pandemic, postal workers have been on the front lines, considered "essential workers" who must continue to do their jobs as usual while others stay home. But some lawmakers are warning that without more support, the U.S. Postal Service (USPS) could completely shut down in the next few months, threatening the livelihoods of hundreds of thousands of Americans.

Last week, Representatives Carolyn B. Maloney, the chair of the Committee on Oversight and Reform, and Gerry Connolly, chair of the Subcommittee on Government Operations, said in a letter to Senate Majority Leader Mitch McConnell that the COVID-19 crisis is threatening the future of mail service in the U.S.

"The Postal Service is in need of urgent help as a direct result of the coronavirus crisis," they said. "Based on a number of briefings and warnings this week about a critical fall-off in mail across the country, it has become clear that the Postal Service will not survive the summer without immediate help from Congress and the White House. Every community in America relies on the Postal Service to deliver vital goods and services, including life-saving medications."

The lawmakers said USPS, which is a quasi-governmental agency that relies on fees rather than taxes, may be forced to shutter as early as June, less than three months from now. They noted that postal workers delivered more than a billion shipments of prescription drugs last year, and ceasing operations during the virus outbreak could have dire consequences for the health of people around the country.

"The Postal Service needs America's help, and we must answer this call," they said.

"These negative effects could be even more dire in rural areas, where millions of Americans are sheltering in place and rely on the Postal Service to deliver essential staples," the lawmakers warned.

Americans are also counting on postal service workers to deliver millions of coronavirus relief checks — a process that won't start until the end of April and isn't scheduled to finish until September. However, it's unclear if it will have the funding needed to do so.

Maloney and Connelly proposed a bill that would provide a $25 billion in emergency funding for the postal service, eliminating its debt with the stipulation that it would prioritize medical deliveries during the crisis. They said the funding would save the jobs of more than 600,000 Americans.

A USPS spokesperson told CBS News on Friday, "The United States Postal Service appreciates the inclusion of limited emergency borrowing authority during this COVID-19 pandemic. However, the Postal Service remains concerned that this measure will be insufficient to enable the Postal Service to withstand the significant downturn in our business that could directly result from the pandemic."

The statement continued, "Under a worst-case scenario, such downturn could result in the Postal Service having insufficient liquidity to continue operations."

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According to the spokesperson, USPS has experienced a significant loss in needed revenues during the pandemic and subsequent decline in economic activity, but it continues to work with lawmakers to ensure Americans' access to mail during this time.

However, when President Donald Trump signed into law the $2 trillion coronavirus emergency spending bill, it allowed USPS to borrow just $10 billion from the Treasury Department.

"That is woefully inadequate," said Fredric V. Rolando, president of the National Associated of Letter Carriers, in a plea for more funding in the next round of legislation. "The administration clearly does not understand the importance of the Postal Service, especially now."

Democrats are working to put together a fourth coronavirus spending bill that would give USPS more funding, primarily in order to boost the ability to vote by mail in the upcoming election, House Speaker Nancy Pelosi said.

Post offices have so far remained open throughout the crisis, along with hospitals, pharmacies, supermarkets and other essential businesses. According to a New York Times report, at least 20 postal workers had tested positive for the virus by last Friday — a number that has likely increased given the rate of U.S. diagnoses.

With over 266,000 confirmed positive tests, the U.S. now has the most cases of COVID-19 in the world, contributing to the global total of more than 1 million cases, according to data compiled by Johns Hopkins University. So far, over 6,900 people have died in the U.S. from the virus.