Mayor Bill de Blasio has spent the least on digital advertising out of all the 20 Democratic presidential contenders who participated in the debates — including just $915 on Twitter ads.

The term-limited pol has refused to say how much money he has raised for his quixotic campaign until he’s forced to disclose donations to the Federal Election Commission on July 15, but if his online ad spending is any indication he’s strapped for cash.

Since launching his long shot 2020 bid on May 16 de Blasio coughed up just $915 for Twitter ads, $25,000 for Facebook ads, and $55,700 for Google ads, according to publicly available data provided by the companies.

“It’s comparable to a congressional-level campaign rather than a presidential one,” said Marne Pike, CEO of the Washington, DC-based online advertising firm Veracity Media.

“Compared to what the other [presidential] candidates are spending it’s pennies,” Pike said about de Blasio’s outlays.

A de Blasio campaign spokeswoman declined to comment.

The next lowest spender was Ohio Rep. Tim Ryan with $121,000.

Only Florida Mayor Wayne Messam and former Pennsylvania Rep. Joe Sestak — who did not make the debates — doled out fewer dollars.

Top spenders across the three platforms were former Vice President Joe Biden at $2.8 million, Sen. Elizabeth Warren at $2.4 million then South Bend, Ind., Mayor Pete Buttigieg at $2.1 million since May 2018.

“The spending on digital is a tactic to either get on the debate stage or to raise money from emails,” said Pike.

President Donald Trump blows all the Democrats out of the water with $4.7 million in digital ad blitzes for his reelection campaign.