One of the measures of a campaign's viability is money, even when the candidate is Bernie Sanders, and he's certainly got a great start toward building momentum.

It's going to take a ton of small donors to keep it going, but no matter who the candidate is, this is good for our democracy.

Advisers to Bernie Sanders have argued that his grassroots network of small-dollar donors could raise him the roughly $50 million the independent senator from Vermont will need to run a credible, competitive campaign in the Democratic presidential primaries.

They may be right.

On Friday, the Sanders campaign announced that it has raised more than $1.5 million online in the 24 hours since he announced his candidacy. It is a surprisingly heavy haul for a candidate whom some in the Democratic chattering class have cast off as a gadfly and viewed as unable to wrest the nomination from the overwhelming favorite, Hillary Rodham Clinton.

The donations came from a broad base of supporters -- some 35,000 donors who gave an average of $43.54 a piece, according to the Sanders campaign. The campaign also said it signed up more than 100,000 supporters through its website, building what it calls a "mass movement."