Robert Cialdini outlines six weapons of influence in his book Yes!: 50 Scientifically Proven Ways to Be Persuasive. One of these concepts that influence people is social proof.
Political campaigns experience social proof all of the time. Candidates who raise a lot of money are able to attract even more contributions because donors are chasing early money. The field organizer that recruited the most volunteers last week will likely be a top performing this week and the weeks following because volunteer beget more volunteers and momentum builds on itself.
Social proof applies to campaign signs too. The more signs on private lawns the more other voters will want their own campaign sign and the more voters will believe your campaign has popular support.
Voters are subject to social proof and the herd mentality. If it’s clear the candidate has a lot support because there is a yard sign on most lawns, undecided voters will take this level of support into account as they are deciding who to vote for.
Voters who support the other candidate will also see the yard signs and it will demoralize them. While the signs won’t change their minds, it might keep them home because they believe the candidate that they support doesn’t have a chance to win.
Social proof is a powerful force that will influence voters, so think about how the campaign can incorporate into the campaign plan and put social proof into action.