The so-called coronavirus curve is far from flat, but for many of the country’s arts organizations, revenue certainly is.

Ticket sales are practically nonexistent. Parents are requesting refunds for children’s dance classes. Any live event scheduled for before June is probably canceled, including springtime black-tie galas, which often bring in large chunks of revenue for organizations.

So, like other sectors of the economy, arts organizations are turning to local and federal taxpayers for help, trying to make the case that American culture needs a bailout, too.

It has not been an easy sell, coming at a time when many pillars of the economy, from airlines to restaurants to public transportation, are facing existential crises and needing handouts themselves. But it is a fight the country’s museums and performing arts groups are used to waging.

A group representing museums, backed by some Democratic lawmakers in New York and elsewhere, have asked for $4 billion in the federal stimulus package, a dream number few believed would win broad support. The bill introduced by the House Democrats includes $300 million for the National Endowment for the Arts and another $300 million to the National Endowment for the Humanities, which each can pass on the money to institutions that need it. The Senate bill, delivered by Republicans, puts those numbers at $100 million each.

Even in normal times, the federal government gives little support to cultural institutions, apart from the Smithsonian, which was created by Congress. Frequent proposals by Republicans to cut the budget or eliminate the N.E.A., one of the few sources of public revenue for the arts, have put cultural organizations in a permanent defensive stance. And given the current political climate, where some of the arts have become refuges for the anti-Trump resistance, this state of affairs is unlikely to change.

Ellen Walker, the executive director of the Pacific Northwest Ballet in Seattle, said that a common argument against funding the arts sector during periods of financial hardship goes something like this: Arts groups may be “nice,” but they’re far from “necessary.”

At least one Republican lawmaker, Representative Bill Johnson of Ohio, took that stance as Congress debated how to carve up emergency funding for coronavirus relief, assigning $35 million to the John F. Kennedy Center for the Performing Arts in the House version of the bill.

In an effort to convince skeptics of their importance, cultural institutions have tried to calculate their economic impact in measurable figures that legislators — even those who don’t attend the ballet or the theater regularly — can appreciate. One such statistic: There were 5.1 million jobs associated with arts and culture in 2017, according to the U.S. Bureau of Economic Analysis.

In Seattle, a group of about two dozen cultural institutions — including the Pacific Northwest Ballet and the Seattle Opera — added up their attendance in 2019 and compared it with the attendance at home games for the city’s football, baseball and soccer teams. (Their calculations showed about 3.2 million sports fans, compared with 8.7 million arts attendees.) They planned to send the figures to Seattle City Council members to support a potential relief package for arts groups.

The city, which has been hit hard by the virus, is already further along than most when it comes to offering financial help. Seattle has agreed to waive or defer two months of rent payment for arts groups on city-owned property, and the mayor signed a $1.1 million funding package to support cultural organizations.

But art administrators worry that, when divided among a long list of arts groups, the city funding won’t go far.

“That million dollars is going to go very quickly,” said Kevin Malgesini, the managing director of Seattle Children’s Theater. “I don’t anticipate these adding up to enough to save the theater.”

For the children’s theater, which has already had to lay off three workers after canceling or cutting short seven shows, survival will mean designing a patchwork of different funding sources — including city, county and federal assistance, as well as private donations, he said.

The Metropolitan Museum of Art in New York, which has projected a shortfall of nearly $100 million this year, started pushing the hashtag #CongressSaveCulture. In a letter to congressional leaders, the American Alliance of Museums warned that museums nationwide are losing at least $33 million each day. The Theater Communications Group, a nonprofit that supports community theaters across the country, urged organizations to contact their members of Congress.

“This isn’t a frivolous, fun little thing,” Representative Chellie Pingree, a Maine Democrat and leader of the Congressional Arts Caucus, said on Monday. “This is an employer of a lot of people and a big sector of the economy.”

Nongovernmental funding streams dedicated to Covid-19 relief have already started up, including a $75 million fund set up by the New York Community Trust, which is offering grants and loans to cultural nonprofits as well as social service agencies.

At a time of enormous uncertainty, arts administrators are looking to measures taken during the 2008 fiscal crisis for some sense of how federal funding will work.

In 2009, as part of a larger economic stimulus, Congress appropriated $50 million to the N.E.A. Sixty percent of those funds went directly to grants for nonprofit arts organizations, while the rest went to state and regional arts organizations. The N.E.A. said that the grants helped preserve 7,000 arts jobs.

In Europe, politicians have also recognized cultural workers’ urgent need for support. On Tuesday evening, Arts Council England, which is supported by lottery revenue, announced a £160 million package — some $180 million — to help arts groups and workers in the country.

Support for freelancers, including artists and writers, has been made available in some countries like Germany. In Berlin, they can apply for a 5,000 euro grant, worth about $5,400.

In the United States, arts workers are pushing for any unemployment insurance and sick leave benefits included in federal legislation to be easily available to self-employed artists — people like Vickie Vipperman, an artist from outside Nashville, Tenn., who creates handwoven clothes and accessories. Ms. Vipperman has already lost a third of her annual income from canceled art fairs, and her husband, a guitarist, is seeing gigs disappear.

“It’s an abrupt stop in cash flow,” she said. “They’ve turned off the faucet.”

In the arts world, employees of every stripe have been hard hit, but administrators are also wary of asking for too much from a government dealing with shortages of critical health care equipment like masks, gowns and ventilators.

Ginny Louloudes, the executive director of the Alliance of Resident Theaters in New York, said that it’s already difficult asking the government to support the arts when there’s no pandemic. Now, administrators have to tread lightly.

“We have to realize that the city needs to build hospitals, it needs to staff hospitals, it needs masks,” she said. “We have to be very careful about how we frame the message.”

Alex Marshall contributed reporting.