WASHINGTON — On first glance, Joe Biden’s March fundraising report looks like a shot in the arm for a candidate who had long struggled to raise cash — giving his campaign a swift infusion of funds after sweeping victories on Super Tuesday and besting his January and February totals combined.

But just as Biden was emerging as the apparent Democratic nominee, the newly tapped gusher of money turned into a trickle as the coronavirus pandemic triggered an economic crisis and forced the campaign to rethink its financial strategy at a time when it needed to begin cutting into the formidable advantage accumulated by President Donald Trump and the GOP apparatus behind him.

The former vice president’s campaign announced Monday that it raised $46.7 million in March, its best fundraising month since Biden joined the race almost a year ago, and a dramatic acceleration in his pace after bringing in just under $9 million in January and $18.1 million in February.

But after starting March off strong, the sudden reduction in fortunes during the rest of the month is striking: Though he raised $33 million just days after the South Carolina and Super Tuesday primaries in early March, small-dollar donations slowed as businesses shuttered and millions filed for unemployment.

At a virtual fundraiser last week, Biden proudly said that his campaign had raised $5.3 million in the 48 hours following the endorsements of Sen. Bernie Sanders, I-Vt., former President Barack Obama and Sen. Elizabeth Warren, D-Mass.

But that is comparatively less than the $5 million to $7 million he raised from online donations in the 24 hours after the South Carolina and Super Tuesday contests respectively, proving the increased difficulty of raising large sums of money quickly in the coronavirus era.

Meanwhile, the Republican National Committee and the Trump campaign have built a formidable re-election effort that has raised $497 million this cycle through March. In comparison, the Democratic National Committee and Biden's campaign have raised $283 million combined amidst a tense primary campaign.

The Trump campaign saw only a slight dip in contributions last month, raising $13.6 million in March compared with $14.2 million in February. Both of those months were markedly higher than the Trump campaign’s January fundraising — it raised $6.4 million in the first month of 2020.

Just as it was in position to capitalize on his stunning comeback in the Democratic primary race, Biden's campaign was suddenly forced to do the unthinkable: cancel, rather than add in-person, high-dollar fundraisers; curtail its aggressive email and text appeals for small dollars and even shutter its online retail store, where new merchandise touting endorsements from his former rivals had sold out almost as quickly as it was offered. They have halted shipments of unity T-shirts and other Biden swag “for the safety of the Team Joe Webstore staff.”

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Biden's campaign is also carefully tweaking language of its online fundraising appeals to explain where even a modest $5 donation would go, while reminding supporters that without money they can’t defeat Trump. Fundraising emails now offer the option to opt out for two weeks at a time, acknowledging that the pandemic may have affected the recipient personally, or more simply they may “want to take a break.”

Biden, who has been effectively confined in self-isolation at his home in Delaware rather than on the campaign trail, is also now borrowing a page from Warren’s playbook, calling small-dollar donors to thank them for their contributions.

As the campaign sent its headquarters staff home and shuttered field offices around the country, hiring was essentially frozen for weeks, at a time when it expected to be expanding its workforce to do battle with a Trump campaign that has been working arm-in-arm with the RNC since the president formed his re-election campaign the day of his inauguration.

Campaign officials, while acknowledging the unprecedented situation they face, say they have nonetheless adapted — and note that they have long become accustomed to trailing the pack in fundraising, especially online.

While the Biden campaign also spent heavily in March, it has just as dramatically wound down expenditures since then. Without rallies, there’s no need for expensive chartered flights or rented spaces and infrastructure for multiple rallies a day. The campaign also isn't spending money on television ads, leaving it to outside Super PACs already spending millions to duke it out with Trump allies in battleground states.

And after a pause, the campaign expects to expand its operation soon.

"We are building on to all aspects of the campaign, especially digital, and have begun to hire additional people,” a senior official told NBC News.

While not the same, the campaign says virtual fundraisers Biden has hosted are proving effective with more traditional donors, and that a larger universe of Democrats is stepping up to help.

Obama campaign and administration alums Paulette Aniskoff, Rufus Gifford and Allison Zelman are inviting thousands over the Obama alumni database to a May 1 virtual fundraiser featuring the former vice president and 150 additional co-hosts including former senior Obama adviser Valerie Jarrett, former chief of staff Denis McDonough and the “Pod Save America” hosts Jon Favreau, Tommy Vietor and Dan Pfeiffer.

With less time on the road, Biden has ramped up that schedule of virtual fundraisers, with six coming up just this week. Last week he held four fundraisers that were attended by more than 400 viewers combined, less than the number who attended individual fundraisers in person after his string of victories post-South Carolina. A Detroit fundraiser with Sens. Cory Booker of New Jersey and Kamala Harris of California attracted 350 people on one night, according to the campaign, the largest audience for a fundraiser to date.

The campaign has also only recently begun raising money for the general election, allowing it to return to those who contributed the maximum of $2,800 for the primary to re-up for November.

And Biden is counting on his former rivals even more now, hoping to draw in support from their loyal followings and small-donor lists. Over the last two weeks, Harris co-hosted a fundraiser with Biden, Warren sent out a fundraising email to her supporters, and Sen. Amy Klobuchar of Minnesota and Pete Buttigieg, the former mayor of South Bend, Indiana, called their large-money donors to redirect their contributions to Biden.

Notably absent from the fundraising haul is Sanders, the Democratic primary candidate who brought in the most money from grassroots online donations. Unlike other endorsers, he did not send a campaign email to Biden’s email list or offer to give the campaign access to his massive donor pool. However, Sanders did send a fundraising email through the DNC’s donor list asking them to contribute to their fund to unite Democrats.

Biden aides say they’re tracking how much money fundraisers with endorsers bring in compared to ones held by Biden alone. An LGBTQ star-studded fundraiser this week featuring performances by Kristin Chenoweth and Melissa Etheridge and headlined by Buttigieg, Billie Jean King, Billy Porter gives donors the option to raise $20,000 to co-host or contribute $5,600, $2,800 or $1,000 to attend.

They have also been experimenting with virtual “fireside chats,” question and answer sessions for donors who have a particular interest in discussing certain subjects like entrepreneurship and innovation, a topic for a fundraiser this week. Those interested in foreign policy attended one with former Deputy Secretary of State Tony Blinken last week and one is scheduled this week with former Secretary of State Madeleine Albright.

But there’s no disputing that Biden is at a serious disadvantage now. As John Morgan, a top Biden donor put it: “It’s really hard to raise money without that photograph line.”

“People want to meet him in person, they want to get that picture, they want to be with other people who are like them,” he said.