WASHINGTON - Donald Trump’s campaign expenses more than doubled last month, even as the Republican presidential nominee held his payroll to about 70 employees, aired zero television advertisements and undertook no significant operational buildout across the country for the 2016 White House campaign.

Instead, about half of the campaign’s $18.5 million in spending was vacuumed up by Giles-Parscale, a web design and marketing firm new to national politics, Federal Election Commission filings show. It’s a crossover vendor from Trump’s real estate organization.

The campaign paid Giles-Parscale $8.4 million in July, about twice what the San Antonio firm had collected from it over the course of the preceding year. Brad Parscale, the president, is the campaign’s director of digital marketing.

The big expense came as Trump put a new emphasis on online fundraising, after paying for his primary run mostly out of his own pocket.

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Millions more went to air travel. The campaign paid about $2 million for private jets other than Trump’s own TAG Air, which also collected $500,000.

Some of Trump’s consultants are also mysteriously well-paid.

Chess Bedsole, the campaign’s Alabama state director, was paid $64,000 last month for field consulting. His last campaign payment was for $15,000 in December.

Yet the campaign’s payroll remained thin, and there did not appear to be much new in the way of office leases across the country, including in critical battleground states such as Ohio.

Trump has relied heavily on the Republican National Committee for conventional campaign infrastructure. And he’s boasted of holding the line on his campaign spending. But he’s running critically low on time to build an operation that can compete with Democratic presidential nominee Hillary Clinton.

In addition to being ahead of Trump in polls in key states, Clinton has maintained a staff of about 700 for months, opened up offices across the country and already spent $67 million on general election ads. Trump put out his first ads days ago, spending $5 million to air them in Florida, Ohio, Pennsylvania and North Carolina.

Her campaign spent $38 million in July, about double his spending.

Clinton can afford to spend more than Trump, the July campaign finance reports show. Her campaign raised $52 million while his brought in $37 million for the month, including a $2 million contribution from Trump himself.

The candidates also raise money for their parties, enabling them to ask for contributions far higher than the $2,700-per-donor limit to the campaigns. Overall in July, Clinton raised $90 million for her campaign and Democratic partners, while Trump raised $80 million for the campaign and Republican groups.

Trump did bring aboard some new campaign consultants in July.

He paid $100,000 to Cambridge Analytica, a deep-dive data firm that did business with GOP opponent Ted Cruz. Hedge fund billionaire Robert Mercer, who contributed $2 million to a pro-Trump super political action committee in July, is an investor in Cambridge.

The Trump filings also show some old ties.

Two weeks after the ouster of campaign manager CoreyLewandowski, Trump’s campaign cut his firm, Green Monster Consulting, another $20,000 check. That’s about the same amount it had paid him each month while he was running the campaign.

At the time of the latest payment, Lewandowski was already on the payroll of CNN, where he is a political contributor.

The campaign also paid Trump Organization employee Meredith McIver, who has worked as a Trump ghostwriter over the years. She took credit - and then blame- for writing Melania Trump’s speech at the Republican NationalConvention​ that included similar lines from Michelle Obama’s speech at the 2008 Democratic National Convention.

The campaign valued McIver’s time, accounted for as payroll from the Trump Organization, at $356.01.