Washington (CNN) There's only one key conclusion to be taken from the first three months of Democratic fundraising for the 2020 presidential race: Bernie Sanders is a fundraising machine.

Sanders, the Vermont senator and democratic socialist, raised more than $18 million in the first quarter of 2019 -- $6 million more than his closest competitor, California Sen. Kamala Harris. He ended March with $15.6 million left in the bank, $4 million more than Massachusetts Sen. Elizabeth Warren, who finished second. (Warren transferred more than $10 million from her Senate account in the quarter; Sanders transferred $2.5 million.)

But neither of those numbers are a) the most impressive part of Sanders' fundraising or b) the thing that should scare every other Democrat in the race. This is: 84% of individual contributions to Sanders between January 1 and March 31 were for less than $200 -- an absolutely stunning testament to the depth and breadth of the small-dollar fundraising army Sanders built in his 2016 presidential campaign. (Sanders, as you may have forgotten, raised $237 million(!) in his 2016 primary race against Hillary Clinton.)

What that means, in practical terms, is that Sanders can go back to ALL of the people who gave him less than $200 and ask for some more money. (An individual can contribute $2,800 to a candidate for the primary.) Not all the people who gave money can give again, of course, but many of them can. Another ancillary benefit: Sanders raises much of these small-dollar contributions online -- meaning he doesn't need to spend precious campaign time holding large events (that cost time and money) to woo more well-heeled donors.

What Sanders' first quarter numbers suggest is that he is going to have enough money to run for as long as he wants to run -- whether or not he becomes the nominee. Which, as Jonathan Martin wrote in today's New York Times , is already making some Sanders skeptics very skittish:

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