Democratic presidential candidate Sen. Bernie Sanders, I-Vt., speaks during a campaign rally, Wednesday, February. 5, 2020, in Derry, N.H. (Steven Senne/AP)
CNN  — 

Sen. Bernie Sanders of Vermont raised $25 million in January, his campaign said Thursday, a staggering sum that marks his highest monthly total since entering the race a year ago.

The haul surpassed his totals from the first and second quarters of 2019 combined, and nearly matched his third quarter total of $25.3 million. He led the Democratic primary field with $34.5 million in contributions over the final three months of the year.

Sanders’ campaign spent $50 million during the final quarter of 2019, exceeding its intake, but still began January with $18.2 million in cash-on-hand. His January fundraising figures underscore the enduring power of his grassroots donor base, which will allow him to compete – and spend big – deep into what could be a long and expensive primary contest.

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With big states like California, which votes on Super Tuesday in March, on the horizon, the new money will be crucial in paying for pricey television ad time and a large field operation at a time when billionaire Michael Bloomberg is already spending at an unprecedented clip.

January’s total brings the amount Sanders has raised since entering the race in February 2019 to $121 million. The campaign also reported that January’s fundraising came from more than 1.3 million donations from more than 648,000 people, of which over 219,000 gave for the first time.

“Bernie’s multiracial, multigenerational, people-driven movement for change is fueling 2020’s most aggressive campaign for president,” Sanders’ campaign manager Faiz Shakir said in a statement. “Working class Americans giving $18 at a time are putting our campaign in a strong position to compete in states all over the map.”

The Sanders campaign said virtually all of its donors, more than 99.9%, have not yet given the legal maximum, meaning he is well-positioned to continue posting eye-popping numbers as the campaign moves forward.

Among Sanders’ January donors, “teacher” was the most common occupation and the five most common employers were Amazon, Starbucks, Walmart, the United States Postal Service and Target. The average donation was $18.72.

Since he got in the race, Sanders has continued to break fundraising barriers. The campaign crossed the 5 million individual contribution mark in January, a milestone his aides said no other presidential contender had achieved at a similar point in a presidential campaign. Including January, the campaign has now received 6.4 million individual donations. Sanders was also the first Democratic candidate to have 1 million people donate to his campaign, a benchmark the campaign hit in September. That number has now grown to over 1.5 million people, according to the campaign.

In addition to the news of their massive January fundraising total, the Sanders campaign announced Thursday that it will invest $5.5 million in television and digital ads and hire a significant number of new staff in 10 Super Tuesday states.

The most states targeted in the buy – Arkansas, Colorado, Massachusetts, Minnesota, North Carolina, South Carolina, Tennessee and Utah – are new investments for the campaign, while the buys made in California and Texas expand on previous investments.

CNN’s Gregory Krieg contributed to this report.