The president is currently trailing his Democratic rival Joe Biden in national opinion polls. In 2016 Mr Trump spent $66million (£50.9million) of his personal fortune to secure re-election.
However, it is highly unusual for a sitting president to make substantial contributions to their own re-election campaign.
Mr Trump made the surprise announcement to reporters at Joint Base Andrews outside Washington before departing to deliver a speech in Florida.
Speaking to the assembled journalists he said: “If I have to, I would. But we don’t have to.”
The president added he will do “whatever it takes” to ensure he is re-elected in November.
Donald Trump could put up to $100 million towards his re-election campaign
Trump addressing supporters in North Carolina
In August Mr Biden’s campaign hit a new record by raising $365million (£281.6million) in one month.
The previous high, $193million (£148.9million), was hit by Barack Obama in 2008.
Mr Trump’s campaign has yet to disclose how much it raised in August.
However, the Republicans claim they raised over $76million (£58.6million) during the four day Republican National Convention.
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Speaking to Bloomberg Tim Murtaugh, a spokesman for the Trump campaign, refused to comment on whether there have been internal discussions on Mr Trump donating his own money.
However, he said: “President Trump’s fundraising is breaking records and we are paying close attention to the budget, allowing us to invest twice as much from now until Election Day than we did in 2016.
“President Trump has also built the world’s greatest digital fundraising operation, a dominant ground game, and a third advantage Joe Biden can never match – enthusiasm.”
During his time as president Mr Trump’s net worth has fallen by an estimated $300million (£231million) to $2.7billion (£2.1billion).
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A number of his businesses, including the Trump hotel in New York and Mar-a-Lago resort in Florida, have reportedly been badly hit economically by the coronavirus outbreak.
Mr Biden has focused heavily on the president’s handling of the COVID-19 crisis in his campaign.
The United States has seen more deaths and infections from coronavirus than any other country in the world.
On Tuesday he tweeted: “Unlike Donald Trump, I’ll listen to the experts and heed their advice — especially when it comes to matters of health and safety.
“You should expect nothing less from your president.”
He later added: “This economy may be working great for Donald Trump and his wealthy friends — but it’s not working for the rest of America. It’s time we change that.”
By contrast Mr Trump has been campaigning heavily on law and order arguing he is best placed to keep Americans safe.
The death of George Floyd during an altercation with police in late May sparked huge protests across America, some of which turned violent.
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A number of cities, such as Portland and Seattle, have been seeing regular demonstrations, including clashes with police, since this date.
On Tuesday he tweeted: “Democrats admit that President Trump’s message is “working” on violence coming to the Suburbs in a Looney Biden Administration.
“Plus, Biden just doubled down on forcing Federal control of local zoning.
“This means low income housing and projects. So much for the American Dream!”