AMES, Iowa – Bernie Sanders supporters like to think of themselves as revolutionaries, but what worries Democratic opponents is their more important skill: organizing.

The Feb. 3 Iowa caucuses are too close to call, with different front-runners as each poll comes along, but Vermont Sen. Bernie Sanders has the best shot at winning. That would boost his chances in New Hampshire’s Feb. 11 primary and in the Nevada caucuses Feb. 22. (South Carolina’s primary on Feb. 29 seems locked for former Vice President Joe Biden.)

Sanders v. Trump in November frightens more Democrats than it pleases, but it could happen.

Iowa voters have been subjected to over a year of relentless campaigning, exceeding all previous elections. More ads than usual flood the airwaves, more signs clutter the roadsides, and more events are scheduled across the state each day and night. Most Iowans, no matter whom they support, will tell you that the Sanders team makes the most calls and knocks on the most doors.

Remember, they’ve been organizing here for over four years. In the 2016 caucuses Sanders came within a whisker of beating Hillary Clinton: she got 49.9% of the vote, and he got 49.6. Since that day, Sanders diehards have focused on a first place finish in 2020.

Only two current presidential candidates can pack arenas in Iowa for full-blown rallies. One is the master, Donald Trump, who parachuted in for a rally four days before the caucuses. The other is the democratic Socialist, Bernie Sanders. Others, like Massachusetts Sen. Elizabeth Warren, Minnesota Sen. Amy Klobuchar, and former South Bend, Indiana Mayor Pete Buttigieg, hold town halls, sometimes with standing-room crowds but rarely totaling more than a few hundred. Former Vice President Joe Biden stages some hybrid events that come closer to a rally, but they are a far cry – in size and raw enthusiasm – from what Sanders regularly mounts.

Bernie Sanders, with his celebrity road show and slick organization, has events like the one I attended at the City Auditorium in Ames. All 900 seats were filled and so many people stood in the aisles that Sanders had to quip that he hoped the fire marshal wasn’t paying attention. Hundreds more people listened to an audio feed in an overflow room, bringing the attendance to about 2,000 on a frigid night.

Grammy winning band Portugal. The Man provided entertainment, Oscar winning filmmaker Michael Moore delivered a funny and energizing speech, and Congressional superstar Rep. Alexandria Ocasio-Cortez of New York positively wowed the crowd with lines like, “True democracy has been purchased by the powerful.” The antidote, she reminded the faithful, is “sustained organizing – electorally and beyond.”

By the time 78-year-old Sanders, who began his day at the impeachment hearings on Capitol Hill, stepped on stage, the crowd was more than ready to salute. He congratulated them for participating in the largest outpouring of individual campaign contributions in American history, averaging $18.50 per person, another benefit of organizing.

His organization is envied by some, but resented by others. Staffers in other campaigns have told me the Sanders team doesn’t always cooperate with statewide party planning and is overly protective of its voter lists and data. Nationally, warnings are issued with regularity by some pundits and Democratic voters about the peril of a Sanders candidacy.

Yet, other candidates in the still-crowded Democratic field face an enthusiasm gap. The front-runners, other than Sanders, have eager supporters and passionate crowds. But, thinking back to the way Barack Obama electrified audiences – and the way President Trump energizes his base – only Bernie Sanders comes close.

I’m reminded of a scene in “The Godfather,” in which Michael Corleone speaks with Hyman Roth about the Cuban revolution. “A rebel was being arrested by the military police,” says Michael, “and rather than be taken alive, he exploded a grenade hidden in his jacket. He killed himself and took the captain of the command with him.”

“What does that tell you?” Roth asks.

“They could win.”