With Biden now planning to enter the 2020 presidential race Thursday, according to three Democrats familiar with the preparations, one of the anxiety-inducing questions hanging over his team of advisers is just how much of former President Barack Obama’s record-setting financial operation Biden will inherit now that he is setting off on his own for the first time in a decade.

It is an urgent task, especially for a politician not previously known as a prolific fundraiser. His leading rival in the Democratic primary, Sen. Bernie Sanders, has amassed $26.6 million across his various political committees, including more than $10 million left over from his 2016 presidential run and 2018 re-election in Vermont. Biden begins at $0, and it would take his raising more than $100,000 every day until Christmas just to match what Sanders had banked at the start of April.

“I don’t think the challenge is underestimated by the Biden team,” said Rufus Gifford, who served as the finance director of Obama’s 2012 campaign and is unaligned for 2020.

The incipient Biden campaign has raced to lock down the party’s biggest donors in recent weeks, pressing the message in private calls that the former vice president’s ability to marshal funds quickly will represent the first major test of his run, according to people who have been contacted. Biden’s allies have pointed with concern to the $6 million sums that Sanders and former Rep. Beto O’Rourke generated in their campaigns’ first 24 hours as the high bar against which he will be measured.

Unlike those two rivals, Biden does not have an at-the-ready list of hundreds of thousands of contributors to ply for small donations. He must rely heavily, at least at first, upon an old-fashioned network of money bundlers — political insiders, former ambassadors and business executives who can expedite dozens, if not hundreds, of checks for $2,800 each, the legal maximum an individual can contribute in the primary.

But there is an inherent tension in the pursuit of big money in the current Democratic Party: The more of it that Biden gobbles up, the greater the risk of a backlash from a liberal base skeptical of the influence of the wealthy on the party. For Biden, in particular, it threatens to cut against a “Middle-Class Joe” image that is central to his electoral argument and appeal. Biden will enter the race already facing wariness from some on the left that he is a political and policy moderate with deep ties to moneyed donors and big companies, many of which are incorporated in Delaware, his home state.

Wade Randlett, an early Democratic bundler for Obama in the San Francisco area who is planning to raise money for Biden in 2020, predicted that the “overwhelming share” of top Obama fundraisers would ultimately side with Biden. “He was an enormously valuable and loyal vice president of the man who we all shed blood, sweat and tears to make president of the United States,” Randlett said.

While some top Obama fundraisers are lining up with Biden, there are already defections, in particular to Sen. Kamala Harris of California and Mayor Pete Buttigieg of South Bend, Indiana.

“This is going to be tough. This is going to be a heavy lift,” Gifford said of Biden’s fundraising efforts. “The Obama people are not a given, and they’re going to have to work for them just like everyone has to work for them.”

A spokesman for Biden declined to comment.

Some rivals, led by Sanders and Sen. Elizabeth Warren of Massachusetts, have sworn off attending high-dollar fundraisers to bolster their populist credentials. Supporters of Biden are organizing such events even before he announces, with one California fundraiser lining up contributions in advance to help Biden “make a splash.”

The dueling imperatives were apparent in Biden’s activity in the last week. He rallied striking union workers near Boston Thursday, proclaiming, “Wall Street bankers and CEOs did not build America — you built America!” At the same time, he has been setting up calls with influential political contributors, according to a person familiar with his activity.

It is not just Sanders to whom Biden must catch up financially: No fewer than nine candidates had at least $6 million in cash on hand at the end of March.

Spearheading Biden’s early efforts has been Katie Petrelius, who has worked as the director of development for the Biden Foundation, Biden’s personal charity, according to people familiar with her fundraising calls. Petrelius is installing an infrastructure of regional leaders and deputies across donor-rich swaths of the country.

Publicly, Biden has mused aloud about who will be behind him. “An awful lot of people have offered to help, and the people who are usually the biggest donors in the Democratic Party and, I might add, some major Republican folks,” he said at the University of Delaware in February. Privately, his circle has fretted to supporters about the optics of his early reliance on larger contributors.

Biden was not known as a prodigious fundraiser before he joined Obama’s ticket in 2008, and concerns about his ability to raise the tens of millions of dollars necessary to compete in the 2016 race were a consideration in his decision in late 2015 not to run.

Biden lagged toward the back of the fundraising pack in his failed 2008 presidential primary run, his last solo bid for office. He raised $8.2 million from individual donors in 2007; Obama, then his rival, raised more than $100 million that same year.

Of course, that was before his two terms as vice president. He spent eight years traveling the country as a top surrogate and fundraising draw for the White House.

Denise Bauer, a Democratic fundraiser and former ambassador who said she would raise funds for Biden once he formally entered the race, said in an email she was “quite optimistic” about his finance operation. “From what I understand, they are putting together a first-rate, modern organization,” she said. “This wouldn’t be a rerun of 2008 or 2012, or even 2016.”

Ed Rendell, the former Democratic governor of Pennsylvania, who is helping to put together a Biden fundraiser later this week, said the “mad rush” by the media to judge campaigns on their fundraising was misplaced in a presidential contest because voters are paying such close attention.

“The one race, of all political races, where money is less important is president,” Rendell said, adding of Biden, “If he wins or loses it will not be because he raised — or didn’t — enough.”

Biden re-established his political action committee, the American Possibilities PAC, in mid-2017 and raised about $2.6 million in its first 19 months.

Less than $1 million of those funds came from donors who gave less than $200. For comparison, Buttigieg’s campaign said it had raised $1 million online in the first six hours after he officially announced he was running this month.

For now, Biden retains a limited digital footprint. His PAC has not purchased ads on Facebook, where many other Democrats have been fishing for new supporters, since December. And it has spent less than $50,000 on Facebook since last May, records show. Other candidates have spent twice that much — in a day.

If Biden is to compete financially, his supporters acknowledge he will almost certainly need to establish a broad network of small, online contributors. But his team will not know how the public will respond until he declares his candidacy.

“Everyone thinks Biden can’t get small donors because he’s moderate,” Rendell said. “Baloney!”

Rendell recommended that Biden invest offline, too, pitching an old-fashioned direct mail program to reach older potential donors and tap into the “general consensus” of his electability against President Donald Trump.

“There is enough of a consensus there that those little old ladies — even if they’re a little on the progressive side — would write a $25, $50, $100 check to Joe, maybe four or five times in the next year,” Rendell said.

This article originally appeared in The New York Times.