NEW YORK (Reuters) - In the crucial last weeks of the U.S. presidential campaign, Democrat Hillary Clinton has dramatically widened her advantage over Republican rival Donald Trump in ad spending, according to campaign finance reports released on Thursday.

A combination photo shows Republican U.S. presidential nominee Donald Trump (L) and Democratic presidential nominee Hillary Clinton during their third and final debate at UNLV in Las Vegas, Nevada, U.S. on October 19, 2016. REUTERS/Carlos Barria

The newest filings showed Clinton’s campaign and Super PAC outspending Trump in the first three weeks of October by a factor of two to one on everything from national TV ads to local outreach on smartphone screens.

At the same time, the two Super PACs associated with Trump’s White House bid have seen their fundraising start to stall out, with one of the groups reserving no broadcast or cable ads between Oct. 20 and Election Day, according to data from ad-tracking firm SMG Delta.

Clinton and Priorities USA, the Super PAC that supports her, have spent $360 million on all types of advertising since the beginning of the campaign, said the new reports, which covered spending through Oct. 19.

That total blows away the $147 million spent on advertising by Trump and his two affiliated Super PACs during the same period.

What’s more, for the period beginning Oct. 20 and running through the Nov. 8 election, Clinton and her Super PAC have reserved an additional $55 million in TV ads, according to SMG Delta, including $30.5 million from her campaign and $25 million from her Super PAC.

A Super PAC is a fund-raising group that must operate separately from political campaigns but can raise unlimited sums.

The Trump campaign has committed to spending $32.4 million during the same period, with the Trump Super PAC known as Great America PAC saying it would also contribute another $2.35 million in broadcast and cable ads.

The newest batch of campaign finance filings also reveal that the celebrity businessman’s recent vow that he would contribute in excess of $100 million to his campaign out of his own fortune has also fallen short.

Trump contributed $56 million through the end of September, chipping in an additional $31,000 since then.

Spending on television commercials does not decide an election. Trump, with his controversial statements and inflammatory tweets, has mastered the art of garnering free media coverage, which is expected to top $5 billion by Election Day, more than double the amount Clinton is likely to earn, according to data analytics tracker mediaQuant.

But ever since Trump’s campaign began to falter last summer after he criticized the family of a slain U.S. soldier, Clinton has been able to use her ad spending juggernaut to repetitively pound at criticisms of Trump, which several strategists said had exacerbated his slide in polls, where he now lags Clinton by eight percentage points.

Trump could pour more money into his ad operation in the final 11 days of the campaign. Republican presidential campaign operatives said areas where Trump could still spend included battleground states, national ad buys and digital outreach and phone banking.

But they also said it may be too late for such outlays to make a difference.

“The stations would gladly take his money,” said Fred Davis, a major Republican ad maker. “I just don’t think he will.”

During the Republican nominating contests, Trump vanquished 16 opponents in part by eschewing campaign finance mainstays such as ads and pollsters.

“He felt he won the primary with basically no ad spending by being a larger-than-life TV personality. It worked,” Davis said. But the general election, he added, was “a whole new ballgame.”

ADS DON’T MATTER ‘UNTIL THEY DO’

Many of Clinton’s TV ads have focused on upbeat messages featuring her work on behalf of women and children. She’s also spent a large amount of her advertising budget attacking Trump, including a commercial that showed children listening to some of his most demeaning remarks about women.

Trump’s ads, by contrast, paint a dark picture of America, besieged by violence and on the brink of economic destruction.

Rick Wilson, a former strategist for Republican Mitt Romney’s 2012 campaign, said “ads don’t matter, until they do,” adding that comments by Trump that critics have called racist and sexist were providing maximum ammunition for Clinton.

Trump may not be able to rely on his small cadre of big donors, either: Make America Number 1 PAC – a super PAC formed by conservative mega-donor Robert Mercer - raised nothing between Oct. 1 and 19.

At the same time, Trump has also stopped doing high-dollar fundraisers.

Overall, the reports released on Thursday night showed how much Trump and his lean campaign operation have been dwarfed by Clinton’s big money juggernaut. In total, Trump has raised $292 million between his campaign and affiliated Super PACs, including his own contributions, whereas Clinton has hauled in more than twice that, at $718 million.