Major donors from both parties already are beginning to scale back after years of riding high off of a booming stock market, donors and fundraisers told POLITICO.

"I’m personally postponing anything where more than two people need to get together until we have an understanding of what the dangers are. And in terms of spending money, I’m trying to cut back as much as possible," said Democratic megadonor and philanthropist Bernard Schwartz, who has given at least $2.8 million to Democratic causes this cycle, including helping a pro-Biden super PAC.

Biden and Trump are starting to work donors via the phone and video meetups, while anxiety rattles through congressional campaigns and some organizations grow nervous about whether they will be able to stay in the black.

It won't take long until campaigns feel the sting, said Amanda Litman, co-founder of Run for Something, which supports down-ballot candidates.

"I think the thing people don’t realize is that campaigns and organizations — both political and nonprofits — don’t keep that much cash on hand," Litman said. "You’re running month to month. One bad month, you can make it through. Two or three, and it can be catastrophic."

Run for Something has canceled events through mid-June, which Litman estimated will cost the group $450,000, approximately 25 percent of its budget for the year.

Both Trump and Biden, who is just beginning to gear up for a general election as the coronavirus rocks the United States, are trying to keep growing their campaigns. And the committees and campaigns associated with House and Senate candidates have canceled almost all upcoming events, they told POLITICO.

“Safety is more important than fundraisers or negative ads,” Jesse Hunt, a spokesman for the National Republican Senatorial Committee, said in a statement. “In-person fundraisers have been canceled and that will affect our bottom line. And we couldn't care less.”

“This decision will cost us money,” Scott Fairchild, executive director of the Democratic Senatorial Campaign Committee, wrote in an email to online donors explaining the committee was canceling all events. “A large chunk of our fundraising is going to dry up. And to compensate for this shortfall, our Democratic Senate campaigns will need the support of this online community more than ever.”

Trump’s campaign has canceled a slew of events, including a pair of highly anticipated fundraisers featuring Melania Trump — her first for the reelection campaign — this week in Beverly Hills and next week at Trump’s Mar-a-Lago resort. Trump also last week canceled a trip to Las Vegas for a fundraiser hosted by casino mogul and Republican megadonor Sheldon Adelson.

“Trump’s fundraising juggernaut is certainly going to slow a bit as the country focuses on survival,” said Republican donor Dan Eberhart. “It may not be evident today, but campaign fundraising is certain to take a hit like every other sector of the economy. There is too much uncertainty for large and small donors alike.”

Both Trump and Biden will keep raising money online and via “virtual fundraisers,” held most often through video conferences with donors. Biden has one such virtual event scheduled for Friday. (The transition hasn’t always been easy: The Biden campaign postponed one such event scheduled for this week in New York City amid technical difficulties, CNBC reported.)

Earlier this week, the Biden campaign distributed a fresh list of incentives to its top fundraisers to try to keep money flowing in: perks for bundlers who raise $25,000 to $500,000 for the campaign. A fundraiser who raises $25,000 for Biden, known as an “Advocate,” gets “direct contact with Regional Finance Director” and “Inclusion in national leadership councils.” People who raise more money for the campaign — including the $250,000 “Scranton Circle” and the $500,000 “Philly Founder” — receive more perks, including “bi-weekly update calls with campaign leadership” and invitations to quarterly and annual finance committee events.

“It may become more 'social distancing' or more draconian down the road, then eventually people will realize we need to move forward with the campaigns as well. Some of that means resources,” said John Atkinson, a Chicago-based bundler for Biden.

Meanwhile, some big-name Democrats expected to spend huge sums on 2020, including Silicon Valley investor Ron Conway and businessman Mike Bloomberg, have turned their attention to combating coronavirus. Neither Conway, nor Bloomberg has announced plans to scale back on politics, but to some, the 2020 election suddenly seems like a more distant priority than a few months ago.

Todd Schulte, president of the Mark Zuckerberg-backed FWD.us, implored lawmakers to use their small-dollar donor lists for advocacy instead of fundraising in an email to supporters about helping with coronavirus, obtained by POLITICO.

“Use your email lists,” Schulte wrote. “I don’t think I got a single email saying call X member and demand ‘more kits everywhere, mass investment in medical capacity, $1000 to every American, mandatory sick leave, and more.’ No one is going to give much online -- to you or your opponent,” Schulte wrote.

Some candidates are letting their small-dollar donors off the hook. Sen. Tina Smith (D-Minn) included a note to donors about the financial toll the emergency is taking in fundraising emails. “It’s okay not to donate right now,” one email from Smith read. Former Colorado Gov. John Hickenlooper, who is now running for Senate, and MJ Hegar, a Democratic Senate candidate in Texas, gave donors the ability to temporarily opt out of fundraising emails during the emergency.

Not every candidate, though, has abandoned raising money in person.

GOP fundraiser Alexandra Kendrick said that while the vast majority of her clients have canceled fundraisers — including Texas Sen. Ted Cruz, who was slated to host a weekend donor retreat in Napa next weekend — two candidate clients are currently planning on going forward with their events.

“If it’s me and them sitting at a table with a chicken sandwich, so be it,” Kendrick said. “It’s not about the money, I think. It’s about the routine for them.”

Alex Isenstadt contributed to this report.