As far as I'm aware, it was a combination of unemployed worker protests combined with WWI veterans demanding their bonus certificates be cashed early, known as the Bonus Army, marching to the capital. Both of which were motivated by the economic depression of that time.
From the first link, I did spot one communist protest in Rhode Island that was 10k strong, as well as a protest in Boston, Massachusetts that was 40k strong against capitalism (though it does not specify if it was communist).
so it is implied that this requires more than voting.
As I mentioned in my previous comment, the thing that really pushed FDR to do the right thing after he was elected was the powerful protests, but I would maintain that had the protestors not voted out of principle and Hoover had won instead, it is likely not much would've been done to alleviate the suffering and conditions those protestors were protesting. Hoover publicly denounced every positive effort put forward by FDR. He also showed how he would've dealt with more protests had he stayed in power from his treatment of the Bonus Army.