Republican Donald Trump could go down as the least well-funded presidential candidate in recent campaigns - entering the final month of the election still without the cash to match the level of staff and advertising that has helped power the campaign of his Democratic rival Hillary Clinton.

With less than three weeks until the election, it is too late for Trump to amass the amount of cash he would need to unleash a spending assault that might turn his hobbled campaign around. Through the end of September, Trump raised a total of $163 million - a far cry from Clinton’s $449 million.

Trump, a New York real estate developer who has boasted about his wealth, pledged to use millions of his personal assets to fund his campaign. In addition to the $163 million raised, he put in $47.5 million during the primary and then added another $8.6 million.

Trump’s fundraising deficit has resulted from a series of campaign crises that made wealthy donors reluctant to contribute to his campaign and reflects that he does not enjoy working the fundraising circuit or calling large-dollar donors to ask them to write checks.

That’s a big disadvantage for Trump. And it shows in how he has been outspent trying to win the Nov. 8 election for the White House, particularly in the two largest spending categories: staff and television commercials.

When it comes to staff, Trump has spent $5 million, compared with Clinton's spending of about $38 million.

Trump had 168 people on his payroll in September, more than doubling the 82 he had on staff in July. Additionally, Trump spent $5 million on field consultants, part-time workers who are not part of the main staff.

Clinton had 815 people on her staff in September.

On advertising, Trump has spent $48.7 million while Clinton has spent $204 million - allowing her to blanket the airwaves with a deluge of advertisements.

It has also allowed Clinton to inject more money into states that have become closer as Election Day nears. Earlier this week, Clinton’s campaign announced it was spending an additional $2 million in Arizona, a late-game decision to try to win a traditionally Republican state that now appears within her grasp.

Overall, Trump has spent about $190 million by the end of September, compared with Clinton's $401 million.

Trump and Clinton can collect donations up to $5,400 from a single individual, but can also collect larger checks that are then divided between the campaign and joint fundraisers with the national and state parties.

The funds that candidates raise for the national and state political parties are still used for the common effort of hiring staff and getting voters to turn out to the polls. But those funds cannot be used in the most direct parts of running a campaign, like buying television ads or hiring staff that report to the campaign manager.

Trump’s campaign struggled to get organized and build out the infrastructure that is needed to be competitive in the key battleground states. Instead, Trump has been dependent on the infrastructure built by the Republican Party.

Trump has raised $244 million through joint fundraising committees with the national parties, of which he got $71 million.