Ad spending on the 2020 Democratic Party presidential primaries has surpassed $1 billion — a record-shattering number with four months to go before the Democratic Party convention, a new analysis released Thursday reveals.

Billionaire former three-term New York City Mayor Mike Bloomberg has already spent $539 million on ads, the report by Advertising Analytics found. It had been previously reported that Bloomberg broke the record for TV and radio ad spending for a presidential campaign.

“Michael Bloomberg is the $500M+ elephant at the center of the Democratic primary and has fundamentally changed the election with his billions,” the study said.

“Since his announcement the week of November 25 2019, Bloomberg has spent an average of $37.4M/week on TV, radio, and digital (he was only off air the week of Christmas). In 2018, a record-breaking year for political advertising, only two candidates spent more during their entire campaigns than Bloomberg is averaging per week,” the analysis added.

Bloomberg’s $539 million in ad spending is $201 million more than President Obama’s 2012 campaign for president, which spent $338 million, the report said.

Bloomberg has also nearly doubled the cumulative total of the field. He has outspent all rivals combined by $209 million.

Candidates and outside groups in total have spent $375 million more on TV and radio than the entire 2016 primaries for both Democrats and Republicans, the report said.

In addition, $262 million has been spent on digital ads this cycle — data that was not available to track in the 2016 race.

Another billionaire, Tom Steyer, has spent $186 million on ads, with poor results in the early voting states thus far. He is expected to fare better in the South Carolina primary on Saturday.

Bloomberg will appear on the ballot for the first time next Tuesday — known as Super Tuesday — when 14 mostly southern states hold their Democratic primary contests – including delegate-rich California and Texas.

Meanwhile front-runner Bernie Sanders has spent $48 million on ads to this point — fueled by contributions from his army of committed small donors — an impressive figure that still pales to spending by the self-financed Bloomberg and Steyer.

But the report says the Vermont senator and self-described democratic socialist is getting a good bang for his buck — spending less on ads per vote received than the other candidates when he won the New Hampshire primary and Nevada caucus and got the most votes in the Iowa caucus.

“Bernie Sanders has generated a grassroots movement that has turned his campaign into a financial behemoth that is quite active in the large and expensive Super Tuesday states,” the analysis said.

As for the other candidates: former South Bend Mayor Pete Buttigieg has spent $35.4 million in ads, followed by Massachusetts Sen. Elizabeth Warren, $23.8 million; Minnesota Sen. Amy Klobuchar, $15.9 million and former Vice President Joe Biden, $13.9 million.

Candidates and outside groups have spent a total of $247 million in Super Tuesday states, up from only $30 million in 2016. Of that total, $110 million in ads have targeted California and $61 million in Texas.

The $1 billion figure in spending includes digital ads as well as TV and radio spots.