Both Democratic presidential candidates Pete Buttigieg and Andrew Yang have received fundraising spikes at the end of 2019. 

Buttigieg, the little-known former Indiana mayor who started the year with no national profile astonished the world after declaring that he raised 76 million U.S. dollars in 2019 on his Twitter. He raised 24.7 million U.S. dollars in the final months of 2019.

The former mayor and Afghanistan war veteran was previously criticized for fundraising in a "wine cave," which led to repeated attacks in December's primary debate. In his tweet, the 37-year-old pointedly noted that his average donation was 38 U.S. dollars.

Rival Elizabeth Warren scorned the news, saying that "billionaires in wine caves should not pick the next president of the United States" and added she was not taking part in big money fundraising events.

"When a candidate brags about how beholden he feels to a group of wealthy investors, our democracy is in serious trouble," she added.

The fundraising spike is expected to power Buttigieg's campaign. He is already topping the polls in the first voting states of Iowa and New Hampshire, and having decided against running for a third mayoral term is now free to devote more time to his campaign ahead of the first caucuses on February 3.

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Buttigieg is not the only outsider candidate to receive a fundraising boost. Tech entrepreneur Andrew Yang's campaign reportedly raised 16.5 million U.S. dollars in the final quarter, including four million U.S. dollars in the final week of the year.

The donations will ensure Yang, another surprisingly successful story of the Democratic campaign to date, will have the resources to stay in the race deep into voting season.

Bernie Sanders raised 34.5 million U.S. dollars in the last three months of the year, he announced on Thursday, while Warren and Joe Biden are yet to release their figures for the fourth quarter.

(Cover: Democratic U.S. presidential candidates entrepreneur Andrew Yang (L) speaks as South Bend Mayor Pete Buttigieg listens at the 2020 campaign debate at Loyola Marymount University in Los Angeles, California, U.S., December 19, 2019. /Reuters Photo)