Tom Steyer, the California activist billionaire who has largely been a nonfactor in the Democratic primary campaign, dropped out of the race on Saturday night.

Steyer's departure came after a disappointing finish in the South Carolina Democratic primary. With 70 percent of the vote in, Steyer had just 11.5 percent of the vote — despite spending millions of dollars on campaigning there.

"There’s no question today that this campaign, we were disappointed with where we came out," Steyer told supporters in Columbia, S.C.

"But I said if I didn’t see a path to winning that I'd suspend my campaign, and honestly I can't see a path where I can win the presidency."

His exit came after he'd spent a total of $158 million on television and radio ads, according to Advertising Analytics. In South Carolina alone, Steyer had spent nearly $21 million as of Tuesday, the firm said.

Steyer had essentially put all of his efforts in recent weeks into South Carolina. He'd shown promise in recent polling in the Palmetto State and invested more time there than any of his competitors. His wife, Kat Taylor, even moved to Columbia earlier this month.

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Steyer had initially opted against entering the presidential contest before reversing course and joining the large field in July. He spent exorbitant sums of his own money on the race, outpaced in the Democratic field by another late-entrant, former New York City Mayor Mike Bloomberg, the billionaire media mogul.

Steyer based his candidacy on promising to declare a "national emergency" on climate change upon taking office, racial justice, and ideas like allowing voters to make laws directly through regular national referenda. He also was a proponent of impeaching President Donald Trump. Former rivals thanked Steyer for his contributions to the race in tweets late Saturday.

Steyer was able to become a regular participant in the Democratic debates, though some his rivals charged that he was simply buying his way onto the stage.

The state Steyer zeroed-in on and saw the greatest return on his investment was South Carolina, where he consistently polled among the top three contenders.

As of Tuesday, Steyer had held 63 events in South Carolina, according to an NBC News count — far more than any of his competitors. He also had hired more than 80 staffers in the state — also more than any of his competitors.

Asked about Democrats thinking he should drop out of the race due to little visible path to the nomination, Steyer told NBC News in an interview he didn't care for what "the Democratic establishment" thinks of his strategy and said it was "a crazy statement" to claim he was serving as a spoiler for former Vice President Joe Biden.