How much does a spot on the presidential debate stage cost? For Tom Steyer, who failed to make the cut, it’s apparently more than $15 million.

Steyer spent roughly that much on ads promoting his long-shot campaign over the past six weeks, but barring a last-minute miracle, the San Francisco megadonor and former hedge fund chief will be shut out of next month’s primetime debate.

He isn’t the only candidate who’ll be watching from the sidelines. Half the field came up short, including New York Sen. Kirsten Gillibrand, who announced Wednesday afternoon she was dropping out of the presidential race — a sign of how crucial the debates have become with 20 contenders scuffling for the spotlight.

But Steyer came the closest. As of Wednesday’s deadline to qualify for the September showcase, he had gathered the required 130,000 individual donors and needed just one more qualifying poll putting him at 2 percent or higher. But that last poll proved elusive, and two national surveys released Wednesday morning found him at less than 1 percent.

“While we believe that voters in (early) states deserve to see Tom on the debate stage in Houston, we understand the rules established by the DNC and respect the process,” Steyer campaign manager Heather Hargreaves said in a statement, acknowledging his near-miss.

Ten candidates have punched their ticket for the debate: Former Vice President Joe Biden, Sen. Bernie Sanders of Vermont, Sen. Elizabeth Warren of Massachusetts, Sen. Kamala Harris of California, South Bend Mayor Pete Buttigieg, former Texas Rep. Beto O’Rourke, Sen. Cory Booker of New Jersey, Sen. Amy Klobuchar of Minnesota, former housing secretary Julián Castro and entrepreneur Andrew Yang.

Steyer’s potential place on the debate stage came with big implications for the rest of the field. If he had become the 11th candidate to qualify, the face-off would have been split into two nights, on Thursday, September 12 and Friday, September 13, with network host ABC randomly dividing the candidates between the evenings. Now all 10 contenders will compete head-to-head on Thursday.

A two-night event would have given each hopeful more time to talk — but it would also have likely deprived voters of the chance to see all of the top contenders debate each other directly for the first time.

Getting bumped to the Friday night debate would also have been unlucky for any candidate — and not just because it’d be held on Friday the 13th. It’s likely that more Americans will tune in Thursday instead of spending their Friday night listening to the finer points of Medicare-for-All or border policy.

The good news for Steyer and others left out — like Hawaii Rep. Tulsi Gabbard and author Marianne Williamson — is they have a better chance of finding their way onstage in October. That debate has the same qualification requirements, and will give them additional time to rack up more polls.

Even without a debate spot, Steyer has changed the presidential race with the magnitude of his spending. He outspent every other Democratic candidate on ads so far, coughing up about $10 million to blanket the airwaves in early states like Iowa and New Hampshire with spots tarring President Trump as “a fraud and a failure.” He’s also led the candidates in social media ad spending, doling out $4 million on Facebook ads and $1.5 million on Google and YouTube ads, according to the companies.

Those tactics could push other candidates to buy more ad time, strategists predict. Steyer has said he plans to spend at least $100 million of his own fortune on the primary campaign.

Steyer’s spending has been concentrated in the four early states, and the polls reflect that: Several have found him near or ahead of more prominent candidates like Buttigieg and Booker in those states, even as he trails badly nationwide.

But barely any early qualifying state polls were released in August — and none since Aug. 8, the last time Steyer got 2 percent. His campaign called on Democratic National Party leaders to expand the approved pool of polls, to no avail.

Gillibrand’s campaign started with big expectations for the New York senator, but she failed to gain traction despite a focus on women’s rights and issues such as paid family leave. Now, she plans to devote her time to helping more women get elected to Congress.

“I believe I can best serve by helping to unite us to beat Donald Trump in 2020,” Gillibrand said in a video posted on Twitter. “It’s important to know when it’s not your time.”