Billionaire Michael Bloomberg, whose 2020 Democratic presidential campaign has already spent $270 million on advertising, has surged to fourth place nationally, according to a poll released Tuesday.

The former three-term New York City mayor finished behind former Vice President Joe Biden at 29 percent, US Sen. Bernie Sanders of Vermont at 23 percent and US Sen. Elizabeth Warren of Massachusetts at 14 percent.

Bloomberg got the support of 12 percent of registered voters, moving him ahead of Pete Buttigieg, who received 7 percent, according to a Morning Consult survey.

The survey found that Bloomberg’s support has doubled in the past month, compared to figures from the same pollsters at the end of December.

His net favorability rating among Democratic and black voters has also increased since he entered the race in November.

Among blacks, it climbed to plus 32 from plus 4 and to plus 33 from plus 5 among Democratic primary voters.

Finishing below Buttigieg, the former mayor of South Bend, Ind., were entrepreneur Andrew Yang at 5 percent, US Sen. Amy Klobuchar of Minnesota with 3 percent, philanthropist Tom Steyer at 3 percent and US Sen. Michael Bennet of Colorado with 1 percent.

Bloomberg, who is worth an estimated $54 billion, according to Forbes, has expanded his campaign staff nationally to around 800 people.

On Monday, his campaign began sending mailers to 2.5 million Democratic primary voters in states voting on Super Tuesday on March 3.

Bloomberg is focusing on the Super Tuesday contests and not competing in Iowa and New Hampshire.

The survey polled 17,863 Democratic primary voters and was conducted between Jan. 20 and 26.

It has a plus/minus 1 percentage-point margin of error.