Hillary Clinton's campaign has more than $42 million in the bank

Donald Trump will embark on the US presidential campaign with a war chest tens of millions of dollars smaller than that of his well-organized rival Hillary Clinton, financial documents filed Monday show.

The presumptive Republican presidential nominee has a mere $1.3 million, according to reports filed Monday night with the Federal Election Commission.

That sum represents an unprecedented low in recent history for a major presidential campaign.

Clinton's campaign -- backed by big donors -- had more than $42 million in the bank as of May 31, its report showed.

Her super PAC (political action committee), known as Priorities USA, has another $52 million, it was reported as saying on Monday.

The news came on the same day Trump dumped his controversial campaign manager as he tried to revitalize his White House bid after recent stumbles.

He has taken a hit in the national polls and prompted outrage with comments about Muslims in the wake of the Orlando gay club massacre.

However Monday's reports reinforce perceptions that his campaign lags woefully behind Clinton's, which is planning to spend more than $100 million on a television advertising blitz ahead of the November election.

Last week Clinton launched a media blitz of ads attacking Trump in eight key states -- Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio and Virginia.

Trump -- who has alienated many traditional Republican big donors and had to lend his own campaign $2 million last month -- is reported to have aired no ads since he clinched the Republican nomination last month.

The financial gap mirrors the organizational one. Clinton's staff of some 700 people dwarfs Trump's skeleton staff of around 70, putting him at a huge disadvantage in the swing states needed to win the election.

Assembling operations on the ground takes time. But Trump's campaign, which has prided itself on its lean organization, is planning to outsource it to the Republican party -- a task it normally does not perform.

The party on Monday reported raising only $13 million during May, about a third of the money it raised in May 2012 when Mitt Romney was the nominee.