Sen. Bernie Sanders (Vt.) speaks at his primary night rally on Feb. 9 in Concord, N.H. (J. David Ake/Associated Press)

At the same moment that Bernie Sanders was declared the winner of the New Hampshire Democratic presidential primary on Tuesday night, Hillary Clinton's campaign released a strategy memo headlined "March Matters." In it, campaign manager Robby Mook pointed out that "the first four states represent just 4 percent of the delegates needed to secure the nomination; the 28 states that vote (or caucus) in March will award 56 percent of the delegates needed to win."

Mook is right. March is when the nomination will be decided. And Clinton carries a clear edge when it comes to the states that will vote next month. For Sanders, March will be a test of whether he is a single-state candidate -- like so many challengers to the establishment favorite before him -- or if he can expand his appeal geographically and demographically and, in so doing, pose a real threat to the former secretary of state.

I dug into the March calendar to figure out how -- and whether -- Sanders might be able to survive and thrive in the states set to vote next month. Here's what I came up with.

There are nine southern states that will vote in March and where Clinton should be heavily favored -- assuming she is able to retain her large lead among black voters. Alabama, Arkansas, Georgia, Tennessee and Texas will vote on March 1. Louisiana will vote on March 5, Mississippi on March 8, and Florida and North Carolina on March 15. Three more states -- Oklahoma (March 1), Virginia (March 1) and Missouri (March 15) -- should lean toward Clinton, demographically speaking.

Give Clinton, at a minimum, 10 wins in March -- including big, delegate-rich states such as Florida, North Carolina and Texas -- and you begin to grasp the daunting nature of Sanders surviving the month as a viable candidate.

Where does he start? Let's take the word of his chief strategist -- Tad Devine -- who laid out a post-New Hampshire case for Sanders in an interview with me last month:

I think we can compete and win in a number of states, like Massachusetts, Colorado, Minnesota and Vermont on March 1, and elsewhere as we move into big battlegrounds like Michigan, Illinois and Ohio.

Vermont seems like a no-brainer. Massachusetts should be another place where Sanders runs well -- although Clinton did beat Barack Obama in the state's primary in 2008. Colorado and Minnesota are caucus states -- more on that in a minute -- where Sanders's grass-roots strength will be a major asset. Michigan (March 8), Illinois (March 15) and Ohio (March 15) feel like a bit bigger stretches for Sanders, although I can see Devine's logic: Big-population states with not massive minority votes. And winning a big state such as Michigan, Illinois or Ohio matters from both a perception and a delegate perspective for Sanders.

But the key for Sanders to survive March almost certainly lies in his ability to win (and win convincingly) in the 10 states that hold caucuses in March. Colorado and Minnesota will hold caucuses on March 1 but the rest of the month's calendar is chock-a-block with other caucus votes: Kansas (March 5), Nebraska (March 5), Maine (March 6) Idaho (March 22), Utah (March 22), Alaska (March 26), Hawaii (March 26) and Washington state (March 26).

The energy and passion Sanders is creating among his supporters should translate well to the caucus process, which, as Iowa showed, requires more time, patience and an ability to persuade than a primary does.  And, unlike in Iowa, these March caucus states won't get the one-on-one attention from the candidates or the saturation coverage from the media -- meaning that organic passion and energy probably will matter more.

Remember that a similar series of caucus wins in February 2008 handed Obama a delegate lead over Clinton that the then-senator from Illinois never relinquished. Although the caucuses are a month later this cycle -- because Iowa and New Hampshire began the process a month later -- they may again play a very important role in the race.

That doesn't mean that Sanders is Obama. Whereas the caucuses catapulted Obama to the top of the delegate count, those same states almost certainly won't do the same for Sanders. For the Vermont socialist, those 10 caucus states function as a sort of lifeline that might allow him to get through March with the outcome of the race still in doubt.

There's no question that Sanders has a path here. But it is by no means a wide one. Circle the caucus states. Sanders needs wins -- and big ones -- badly to push the race to April.