Joe Biden raised a record US$364.5 million last month - dwarfing the $210 million which the White House incumbent raised.
On Thursday, 10 September, Trump's campaign manager Bill Stepien said: "Both campaigns are raising massive amounts of money but have very different priorities about how to spend it. In addition to advertising, President Trump's campaign has invested heavily in a muscular field operation and ground game that will turn out our voters, while the Biden campaign is waging almost exclusively an air war. We like our strategy better.''
These are my real words about our GREAT HEROES, not made up lies by the enemy. THANK YOU and God Bless You All! pic.twitter.com/oFgQXzpJHU— Donald J. Trump (@realDonaldTrump) September 9, 2020
In 2016 Hillary Clinton spent almost double what Trump did - $1.19 billion, compared to $646 million - but it was the Republican insurgent who ended up in the Oval Office.
So winning the fundraising game may not guarantee an election victory.
But who is donating money to the Biden campaign and what do they want out of it?
Much of it comes from individuals who are donating small sums - $10, $50, $100 - often driven by their loathing of the Trump administration, rather than any particularly affection for the 77-year-old former vice president.
But who are Biden’s big donors?
The Center for Responsive Politics has listed the biggest donors to Biden during the 2020 election cycle, many of which are known as super PACs (political action committees).
Sixteen Thirty Fund - $11.2 million
On its website the Sixteen Thirty Fund says: "We help promising leaders and emerging public-interest campaign advocates form meaningful and lasting solutions that improve the lives of all Americans."
That sounds pretty wholesome.
But Robert Maguire, the research director for the watchdog group Citizens for Responsibility and Ethics in Washington, described the Sixteen Thirty Fund in a Politico article as a "dark money" network which allows left-leaning groups to influence campaigns anonymously.
Sixteen Thirty Fund’s executive director is Amy Kurtz, a Washington-based lobbyist who has spent 25 years pushing various liberal causes.
Democracy PAC - $9.75 million
In July it was reported by Politico that George Soros had set up Democracy PAC to support the Democrats in 2020 and had pumped $5.1 million into it, the biggest individual political donation of the campaign at that stage.
Hungary-born Soros, who is now 90, is worth an estimated $8 billion and made his money as a hedge fund investor.
Soros’s Open Society Foundations, a liberal grant-giving network, has channelled $33 million in the past into groups working with the Black Lives Matter movement.
Priorities USA - $9.1 million
On its website Priorities USA says: "The only way to take on Donald Trump and his agenda is to vote him out of office and elect a Democratic candidate for president. Until they are defeated, Trump and his Republican allies in Congress and in states across the country will attempt to implement their agenda, gutting health care coverage for millions of Americans, putting the interests of millionaires above average Americans, and attacking the fundamental rights of immigrants, women and people of colour."
In the past George Soros has donated money to Priorities USA.
On the Opensecrets website Donald Sussman, founder of Connecticut-based hedge fund Paloma Partners, is listed as having donated three separate tranches of $1 million, $2 million and $5 million to Priorities USA.
Sussman, 74, started making money as a 12-year-old when he correctly guessed that the price of sugar would go up after the Cuban Revolution, and was married to Chellie Pingree, a Democrat senator from Maine, between 2011 and 2016.
Euclidean Capital - $7 million and Renaissance Technologies - $4 million
Another huge donor is Jim Simons, an 82-year-old mathematician who is estimated by Forbes to be worth $23 billion.
Simons’ donations have come via his two hedge funds Euclidean Capital and Renaissance Technologies.
Both invest mainly in biotech, artificial intelligence, food and healthcare.
Among those companies Simons has invested in recently are the Swedish AI start-up Peltarion.
League of Conservation Voters - $5.25 million
The League of Conservation Voters, which has been around for 50 years and now has two million members, campaigns on climate change and clean energy and is a natural enemy of the Trump administration, which continues to favour coal mining, oil drilling and fracking.
On its website the LCV says it “drives environmental progress through action” and adds: “Our efforts to protect the environment and engage in the political process are rooted in an understanding of racial, social and environmental justice.”
It has powerful branches in Arizona, Nevada, Colorado and Maryland which reach out to the Latino community under the name Chispa.
American Bridge 21st Century - $4.1 million
Another generous super PAC is American Bridge 21st Century, which was founded in 2010 and claims to be the “largest research, video tracking, and rapid response organisation in Democratic politics”.
Pro-Democrat super PAC @American_Bridge today sent a fundraising email with the subject line: "Get dark money out of our elections!"— Dave Levinthal (@davelevinthal) January 16, 2020
This is curious, because American Bridge has itself long used "dark money."
From @publicintegrity last year: https://t.co/piuRxPrxLW pic.twitter.com/v5mGwMHRQp
It is not clear who is funding American Bridge 21st Century but it says it is focusing its efforts on three states - Michigan, Wisconsin and Pennsylvania, all of which Trump won in 2016.
American Bridge 21st Century was founded by David Brock, who started out as a conservative journalist but in the 1990s, during the Clinton administration, he switched sides and later founded the liberal watchdog Media Matters for America.
Simon Property Group - $4.1 million
The Indianapolis-based Simon Property Group is the largest operator of shopping malls in the United States.
In February the company agreed to buy the rival Taubman Centers for $3.6 billion but backed out of the deal when the coronavirus pandemic hit retail sales.
Marcus & Millichap - $4 million
Another huge donor is Marcus & Millichap, a San Francisco-based real estate firm founded by Greek-American George Marcus.
Marcus - who was born George Moutsanas in Greece during the Second World War - has donated $3 million to a Greek Orthodox Church in New York.
The billionaire donated $100,000 to Hillary Clinton’s campaign in 2016 and during the 2018 mid-term elections he and his wife Judith donated $9 million to the Democrats.
Baupost Group - $3 million
Baupost Group is yet another hedge fund, founded by New Yorker Seth Klarman.
Klarman - who made a lot of money buying distressed assets in the wake of the 2008 financial crisis - is a racehorse owner who won the 2017 Preakness Stakes, one of the biggest races in US horse racing.
Other Big Corporate Donors
Sequoia Capital - $2.55 million, InterSystems Corp - $2.5 million, Bain Capital - $2.2 million, Choice Hotels International - $2 million, Goodlands Management - $2 million
Seth MacFarlane - $700,000
Comedy writer and actor Seth MacFarlane donated $700,000 through his production company, Fuzzy Door.
MacFarlane, who created the Family Guy and American Dad! cartoon series and directed the film, Ted, starring Mark Wahlberg, has been a long-time supporter of the Democrats and a proponent of LGBTQ rights.
As an actor he also played Brian Lewis, the former Executive President of Fox News in the drama The Loudest Voice, based on the sexual transgressions of Fox's founder Roger Ailes, a veteran political consultant and early supporter of Donald Trump.
Steven Spielberg - $500,000
Hollywood director Steven Spielberg donated $500,000 in December 2019.
Spielberg, co-founder of Dreamworks Animation, directed The Post in 2017, a film which centres on a battle between the press and the government and last year he was the executive producer of a documentary which explored humans capacity for “hatred” and how to overcome it.
Kate Capshaw - $500,000
The actress wife of Steven Spielberg donated half a million dollars in December 2019.
She starred in Indiana Jones and the Temple of Doom but retired from acting in 2001.