These six candidates have spent the most money in the race so far. Note: Numbers are cumulative. Candidates are ordered by the total amount spent through January. Mr. Biden entered the race in the second quarter of 2019, Mr. Steyer in the third quarter and Mr. Bloomberg in the fourth quarter.

By the end of January, Michael R. Bloomberg had spent $409 million on his presidential campaign, more than what four other leading candidates — Bernie Sanders, Joseph R. Biden Jr., Elizabeth Warren and Pete Buttigieg — had spent combined since they started running.

Mr. Bloomberg joined the race only in November, while those candidates have been running since last winter or spring. Three-quarters of his spending through January was on television and digital advertising.

[See who led the money race in the first, second, third and fourth quarters of 2019.]

Once again, Mr. Sanders raised the most.

Mr. Sanders, whose campaign is being fueled by contributions from a huge roster of online donors, had the biggest haul in January, according to fund-raising reports filed on Thursday. Mr. Sanders also raised the most in three of the four quarters in 2019. (Mr. Bloomberg, a billionaire, is running a self-funded campaign and is not accepting contributions from donors.)

Amount Raised From Individual Contributions (in millions) Note: Cycle totals include all activity in the 2020 election cycle.

Ms. Warren was low on cash at the end of January.

Among the candidates relying on donors to fund their campaigns, Mr. Sanders had the most money on hand entering February, just before the Iowa caucuses, the first nominating contest of the primary race.

Ms. Warren entered February with only $2.3 million on hand. In January, her campaign obtained a $3 million line of credit and tapped $400,000 of it.

The candidates are in the midst of a costly stretch of the calendar, with the first four contests in February followed by Super Tuesday on March 3, when 14 states have primaries.

Cash on Hand (in millions) Note: Figures are as of Jan. 31. Candidates who are largely or entirely self-funding their campaigns are excluded.

Mr. Buttigieg and Ms. Warren burned through cash at a rapid clip.

Mr. Buttigieg began January with $14.5 million in cash on hand and ended the month with less than half that amount. Ms. Warren began the month with $13.7 million and depleted most of her war chest.

Both campaigns gave a more up-to-date glimpse at their fund-raising on Thursday. Ms. Warren’s campaign said it had already raised more than $17 million in February, while Mr. Buttigieg said his campaign had already raised $11 million.

Burn Rate Note: The burn rate shown is a candidate’s spending in January relative to individual contributions he or she received. Contribution refunds are excluded from the spending figures. The burn rate is greater than 100 percent if a candidate spent more than he or she raised. Candidates who are largely or entirely self-funding their campaigns are excluded.

In January, Mr. Bloomberg dropped about $5,000 per minute.

Mr. Bloomberg’s campaign spent an eye-popping $7 million per day in January — or roughly $300,000 per hour, $5,000 per minute and $82 per second.

He spent more than $8 for every dollar spent by Mr. Sanders, the biggest spender among the candidates relying on donors rather than their own personal wealth.