US President Donald Trump's re-election campaign is set to report raising more than $US30 million ($A42 million) in the first quarter of 2019, edging out his top two Democratic rivals combined.
The haul brings the campaign's cash on hand to $US40.8 million ($A56.9 million), an unprecedented war chest for an incumbent president this early in a campaign.
The Trump campaign said nearly 99 per cent of its donations were of $US200 or less, with an average donation of $US34.26.
Trump's fundraising ability was matched by the Republican National Committee, which brought in $US45.8 million in the first quarter - its best non-election year total.
Combined, the pro-Trump effort is reporting $US82 million in the bank, with $US40.8 million belonging to the campaign alone.
Trump formally launched his re-election effort just hours after taking office in 2017, earlier than any incumbent has in prior years.
By contrast, former President Barack Obama launched his 2012 effort in April 2011 and had under $US2 million on hand at this point in the campaign.
Obama went on to raise more than $US720 million for his re-election. Trump's re-election effort has set a $US1 billion target for 2020.
Trump campaign manager Brad Parscale said in a statement that Trump "is in a vastly stronger position at this point than any previous incumbent president running for re-election, and only continues to build momentum."
Trump's fundraising with the RNC is divided between two entities: Trump Victory, the joint account used for high-dollar gifts, and the Trump Make America Great Again Committee, the low-dollar digital fundraising operation known internally as "T-Magic."
Trump is benefiting from the advantages of incumbency, like universal name recognition and his unrivalled position atop the Republican Party.
Among Democrats, dollars are divided across a candidate field of well more than a dozen, while the Democratic National Committee remains in debt and has suffered from being dramatically out-raised by the RNC in recent months.
Bernie Sanders topped the Democratic field in the first quarter, raising slightly more than $18 million, followed by Kamala Harris with $12 million and Beto O'Rourke with $US9.4 million.
In 2015, Trump swore off outside money, declaring in his opening speech: "I'm using my own money. I'm not using the lobbyists'. I'm not using donors'. I don't care. I'm really rich."
He quickly reversed course on high-dollar donations after he won the GOP nomination, bowing to the financial pressures of running a general election campaign, and he'd already raised millions online through the sale of merchandise like his signature red Make America Great Again hats.
Trump gave or loaned $66 million to his 2016 campaign, but has yet to spend any of his own cash for his re-election effort.