(CNN) Beto O'Rourke raised $9.4 million in the first 18 days of his bid for the 2020 Democratic presidential nomination, his campaign said Wednesday.

The former Texas congressman's haul puts him behind Sen. Bernie Sanders, who raised $18.2 million in the first 41 days of his campaign, and Sen. Kamala Harris, who raised $12 million since launching her 2020 run in late January.

O'Rourke's campaign emphasized the short window between his launch and the close of the year's first fundraising quarter -- noting that his average of $520,000 per day is the most any candidate has raised.

Much of that money has come in two short bursts: The first day of his campaign, during which he raised $6.1 million, and the final weekend of March, when he raised more than $1 million.

Excluding their massive day-one totals -- O'Rourke edged out Sanders' $5.9 million -- Sanders averaged $300,000 per day, while O'Rourke raised an average of nearly $200,000 per day.

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