A Democratic presidential hopeful is fuming over the news that billionaire Tom Steyer already amassed 130,000 unique donors — likely propelling him onto the September debate stage faster than 2020 candidates who have been grinding away on the campaign trail for months.

Montana Gov. Steve Bullock spent Tuesday complaining that Steyer had paid his way to Houston, where the third Democratic debate will be held.

“I think the DNC rules were well-intentioned, but what it really has done is allowed a billionaire to buy a spot on the debate stage,” Bullock said. “Tom Steyer just spent $10 million to get 130,000 — we’re getting to the point where as we’re spending money online as opposed to actually talking to voters.

“Grassroots support and elections are about people talking to people, not billionaires being able to spend a whole lot of money to buy Facebook ads,” Bullock continued.

Bullock, who missed the first debate due to Democratic National Committee rules and who could get cut from the third one, said the rules are forcing campaigns to “spend millions on digital ads chasing $1 donors.”

The DNC put out strict rules for candidates to qualify for the third and fourth presidential debates, which are expected to halve the 24-candidate field.

Democratic hopefuls must amass 130,000 unique donors and get 2% or higher in four distinct polls. The deadline to meet these requirements for the Sept. 12 debate is Aug. 28.

Steyer announced his run on July 9 but hit the donor threshold before the majority of the field. His campaign said he needs just one more poll to cross that goal as well.

Nine candidates have so far met the DNC’s requirements: Joe Biden, Pete Buttigieg, Kamala Harris, Bernie Sanders, Elizabeth Warren, Cory Booker, Beto O’Rourke, Amy Klobuchar and Andrew Yang. Besides Steyer, Tulsi Gabbard and Julian Castro have enough donors.

Steyer’s campaign is pushing back on the charge that his cash played an outsized role. “Fewer than half of Tom’s donations came from advertising,” Steyer’s campaign manager, Heather Hargreaves, tweeted Tuesday. “Writing off the support of thousands of Democratic voters who are responding to Tom’s message isn’t the way to beat Trump in 2020, no matter what you think about the DNC’s criteria.”

The campaign wouldn’t comment on whether the $10 million spending figure for Steyer, first reported by NBC News, was accurate.

On the ground, Steyer doesn’t seem to have anywhere near the same level of support as some of the early debate qualifiers. One Iowa voter told The Post that a Steyer event she attended was as ill-attended as a Sunday morning meet-and-greet for New York City Mayor Bill de Blasio, which attracted about 15 people.

Over the weekend, The Post found two Iowa voters whose first choice was extreme longshot Joe Sestak, a former congressman from Pennsylvania and a veteran, but none for Steyer.

“He’s doing it the way you’re supposed to do it, he’s camping out in Iowa. And talking to the people you need to talk to, but that’s not being rewarded this cycle,” one Democratic aide – working for a different struggling campaign – said of Sestak.

More broadly, the aide worried that the DNC wasn’t giving the candidates enough time to marinate before killing their ability to get national exposure.

“I would say that both candidates in this race and Democratic activists on the ground who actually show up and vote are not happy the DNC is picking winners and losers in August,” the aide said. “So I think the legacy of Tom Perez is that he sold debate spots,” the staffer added, referencing the current DNC leader.