WASHINGTON — Bernie Sanders vowed yesterday that his campaign will go the distance in the Demo­cratic presidential primary. But in reality, Super Tuesday could be Sanders’ last stand.

It’s all a matter of arithmetic.

Sanders’ surge following his strong showing in Iowa and his big win in New Hampshire made him appear to be a formidable challenger to Democratic favorite Hillary Clinton. Sanders was riding a wave made up of equal parts momen­tum, money and grass-roots support.

Then he lost in Nevada.

“Now he has just two of those,” Democratic stra­tegist Steve McMahon said. “He lost momentum to Hillary.”

If Sanders piles up more losses in South Carolina on Saturday and again on Super­ Tuesday, the cash he has amassed in small donations will start to dry up. Without money, the movement won’t be able to sustain itself.

“Bernie Sanders need to demonstrate that he can be competitive in places other than overwhelmingly white states,” said McMahon.

Voters in 11 states and American Samoa go to the polls in the Democratic primary Tuesday, as well as Democrats living abroad. That adds up to 1,004 delegates up for grabs in the race to get the 2,383 needed to clinch the nomination.

To be blunt, the math looks terrible for Sanders­. He has struggled to win over black and Hispanic voters, who make up a large percentage of Southern Democrats. And Super­ Tuesday has been dubbed the “SEC” primary because­ of all the Southern states that hold voting that day, including­ Texas (222 pledged delegates), Georgia (102), Virginia (95) and Tennessee (67).

Sanders isn’t expected to come close to winning any of those states, but he needs to at least make a good showing in all of them.

But that isn’t enough. He also needs to basically run the table with large-margin victories in states where there are far fewer minority voters, like Massachusetts (91 pledged delegates), Colorado (66), Minnesota (77) and Oklahoma (38).

He’ll undoubtedly perform well in his home state of Vermont. Too bad only 16 pledged delegates are up for grabs there.

After Tuesday, there are few opportunities for Sanders­ to make up ground — particularly given Clinton’s superdelegate advantage as well as labor union support in Northern states.

“Unions are spending a lot of money helping Hil­lary,” said Democratic stra­tegist Brad Bannon.

Which leaves Sanders­ with just five days to convince Southern voters that he’s their guy. Given Sanders’­ decision to focus his recent campaign stops in states like Oklahoma and Missouri, it seems even he realizes that’s a long shot.