For months before the conference, activists went door to door, speaking with local residents and building alliances with community groups.
This is exactly the shoe-leather politics that mainstream parties have neglected in the east, ceding ground to the far right.
These efforts paid off. After my blockade broke up, I walked through Erfurt with hundreds of other protesters.
People waved from windows and cheered us on. An older woman leaning on her garden fence, tears in her eyes, gave us the thumbs up.
We were a pack of lefties protesting fascism in the heartland of the AfD. For a moment, we felt like the majority.
Widersetzen did not stop the conference. Delegates slipped into the convention centre before dawn to avoid blockades.
But the movement achieved something mainstream parties have failed to do: convince thousands of ordinary people that democracy requires putting your body on the line.
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It won’t be enough alone to stop the AfD. But after years of seeming inevitability, this felt like the beginning of the fightback.