January 18, 2016 7:37 PM EST

Hillary Clinton and Bernie Sanders are locked in a tightening race for the Democratic nomination, played out in sound bites, statements, and pundits’ proclamations, all viewed from afar. But the action under hot TV lights and at mega-rallies is only half the race.

On the ground Clinton and Sanders have assembled large ground organizations to spread their message and bring voters to the polls. Large teams of organizers are camped out in Iowa, New Hampshire, Nevada, South Carolina, and a slew of other early voting states, bringing on local supporters to phone bank and knock doors for their candidate. In New Hampshire, Sanders’ campaign says he has 6,300 regular volunteers working for the campaign; Clinton says 7,600 Granite Staters have pitched in.

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The canvassers walk door-to-door with a script and clipboard, often recruiting voters with commit-to-vote cards and a check box, often not. Each campaign uses a trove of voter data that tells them the name of the person’s door they are knocking on, and something about their voter history. A successful day of volunteering can yield a half a dozen commitments.

It is the unglamorous drudgery of the door-walking that can win or lose an election, but it largely remains outside the national spotlight.

TIME followed canvassers from both the Sanders and the Clinton campaign in New Hampshire for a day.

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Write to Diane Tsai at diane.tsai@time.com.

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