Donald Trump’s campaign doubled its spending in July, even though the Republican nominee still only employed about 80 people, aired no television ads and maintained ties with his fired campaign manager and the writer who plagiarized part of his wife’s convention speech.

His campaign lags far behind that of his Democratic rival, Hillary Clinton, whose team spent about twice as much as his did last month. Clinton also raised more funds, taking in $52m for her campaign and Democrats, according to July filings with the Federal Election Commission, while Trump raised $37m for his campaign and Republicans.

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Trump’s largest expenses in July were from a new push for online fundraising, as he moved away from donating to his own campaign and more actively solicited money from voters. Trump has given about $52m to his own campaign, but is no longer self-funding the bulk of the effort through loans or donations.

The campaign paid a Texas-based web design and marketing firm, Giles-Parscale, $8.4m in July, about twice as much as it made over the last year. The firm’s president, Brad Parscale, is digital director for Trump’s campaign, and has worked for Trump’s real estate business since 2011.

Trump’s campaign also paid $20,000 to the consulting firm of Corey Lewandowski, the campaign manager he fired in June, two weeks after Lewandowski left the campaign and became a paid pundit on CNN. The sum was roughly equal to how much Trump’s campaign paid him as manager.

The campaign also paid $356.01 to Meredith McIver, an employee of the Trump Organization who took the blame for plagiarizing Michelle Obama’s 2008 convention speech for use in Melania Trump’s 2016 speech. McIver is listed as a co-writer for several of Donald Trump’s books, and because of her work as an “in-house” writer for Trump’s private business, the campaign risked violating campaign laws if it had not separately paid her.

Though the financial documents show little sign that Trump has opened offices around swing states, Trump did show some signs of scaling up for the general election. He paid $100,000 to Cambridge Analytics, a data analysis firm that formerly worked for Senator Ted Cruz and has ties to Robert Mercer, a hedge fund billionaire who supports Trump. He also paid his Alabama state director, Chess Bedsole, $64,000, three times his last payment, in December, even though Alabama has voted Republican for decades.

The campaign paid about $2m for private jets and $500,000 to pay for expenses on Trump’s personal plane. Last month, Trump paid more than $773,000 to companies he owns; since the beginning of the race, his campaign has paid more than $7.5m to Trump companies or those owned by family members. In all, his campaign spent $18.5m in July, including $1.8m on hats and merchandise.

Clinton, in contrast, reported 703 staffers, $2m on travel and signs of new offices. In July, her campaign spent a total of $38m, filings show, mostly on advertising. Last week, Trump spent $4.8m on his first general election ads, which aired in four swing states.

Trump’s personal finances remain mostly opaque, since the candidate has refused to release his tax returns – breaking 40 years of precedent by presidential nominees – and because his business is structured in a labyrinth of holdings, third parties and debt. A New York Times investigation into Trump’s finances found he had at least $650m in debt, far more than he disclosed on earlier FEC forms. Trump has said he will not release his returns while they are under an IRS audit, though no law prohibits that release.

Clinton has released several years of tax returns, including from 2015, when she and her husband made nearly $11m. But she has been haunted by the web of donors, including foreign governments, that give to the family’s sprawling Clinton Foundation. The philanthropic organization has said it will no longer accept foreign donations if Clinton is elected president, but her campaign manager, Robby Mook, refused to say that it would stop taking those donations during the campaign.

Political action committees allied with Democrats were boosted by several billionaires, filings also show. George Soros gave $1.5m to a Planned Parenthood Super Pac and $500,000 to the Senate Majority Pac, and Tom Steyer gave $7m to his own Super Pac, called NextGen Climate Action Committee. Michael Bloomberg gave $5m to his own group, called Independence USA, and though the former New York mayor has endorsed Clinton, his Pac is also working to help Pennsylvania’s Republican senator, Pat Toomey, because of his support for gun control measures.

Conservative billionaires have largely shied from donating to Trump’s campaign, and filings showed that Paul Singer and Charles and David Koch are concentrating on groups to support Senate and House candidates. Mercer, on the other hand, has given $2m to a pro-Trump Super Pac, and also funds Breitbart News, whose boss, Stephen Bannon, took control of Trump’s presidential campaign last week.