WASHINGTON — Hillary Clinton spent $645,000 more a day than her opponent Donald Trump last month, but even with her $50 million campaign outlay, she has not been able to pull away from him in the race for the White House.

Clinton’s campaign had its most expensive month to date in August, eclipsing its previous monthly high by more than $12 million. And combined, Clinton and the national Democratic Party paid out $78 million in August, while Trump and the Republican National Committee spent about $47 million.

While both candidates are raising huge sums from donors, their lopsided spending lays bare the difference in the two major party presidential campaigns. Clinton is running a conventional operation featuring multimillion-dollar ad buys and expansive voter outreach. Trump has kept spending down by enjoying seemingly limitless free media coverage and outsourcing the guts of his voter contact duties to the Republican Party.

The spending disparity has also become a favored Trump boast.

“Our expenditures on advertising, our expenditures on people, our expenditures on everything are a tiny fraction. And yet we’re minimum tied,” Trump said Tuesday at a rally in Kenansville, North Carolina. “If you can spend less and be winning, that’s a positive thing, right?”

Josh Schwerin, a spokesman for the Clinton campaign, said Trump has been “derelict” in building a political operation that would help not only himself but down-ballot Republicans.

Four years ago, President Barack Obama and GOP nominee Mitt Romney each raised and spent about $1 billion, a formidable number that Clinton’s national finance director has also set as a benchmark.

Much of Clinton’s spending has been eaten up by advertising, which is costing her about $10 million per week. Through August, she blanketed 11 states with 35,714 broadcast television commercials to Trump’s 7,457 in five states, according to Kantar Media’s political ad data.

Clinton also has built a robust campaign team of 800 employees who cost a total of about $5 million last month. Even after an August hiring spree, Trump has a far smaller shop of about 130 employees and more than 100 consultants.

Among those consultants: Former campaign manager Corey Lewandowski. He parted ways with Trump in mid-June — and was immediately hired as a CNN contributor — but his Green Monster firm received a $20,000 payment for “strategy consulting” Aug. 11, the same amount it has regularly been paid for months.

The Trump campaign’s biggest expense for the month was more than $11 million to Giles-Parscale for digital consulting and online advertising. Like Trump, the Texas firm is new to politics.

The Clinton campaign’s August fundraising report shows increases in legal and polling expenses, which appear to reflect those firms’ billing cycles. The campaign spent about $450,000 on legal bills and almost $1.3 million on polling.

The presidential spending is even more lopsided after factoring in the main super PACs backing each candidate. While the campaigns must adhere to a $2,700-per-person, per-election donation limit, super political action committees can accept unlimited amounts of money.

Deep-pocketed Priorities USA spent $20.6 million last month, almost exclusively on Trump-bashing and Clinton-boosting TV, radio and digital. The group also replenished its war chest with a healthy $23.4 million haul.

Trump’s outside boosters have so far raised and spent much less money; for example, one group, Great America PAC, spent just $2.6 million in August. Some late help may be on the way: On Tuesday, a group called Future 45 said it has a $5 million commitment from billionaire casino owner Sheldon Adelson and $1 million from members of the Ricketts family to attack Clinton.

Clinton’s aides insist their investments will pay off on Election Day.

“Battleground states carry that name for a reason: They’re going to be close, from now until Election Day,” campaign manager Robby Mook wrote in a memo to supporters this week. “But we are going to win them because we’ve spent the past year building a superior ground game to communicate our message and turn our people out to vote.”

Yet if August finance reports are a guide, her heavy spending is only one piece of the puzzle.

The polls have tightened significantly since Clinton benefited from a post-convention bump in early August. Some surveys still show her slightly ahead, but others show an extremely tight race nationally and in key battleground states such as Florida and Ohio.