What the Fallacy?!
Bandwagon
The Definition
Appealing to the popularity of a policy or candidate as validation that it is the right choice.
The Explanation
Political campaigns often use polls to create a sense of inevitable victory, hoping voters will simply 'jump on the bandwagon' rather than analyze the issues.
Political Example
The campaign's main slogan was, 'Join the millions of Americans voting for Smith!' implying that if everyone else is doing it, it must be the correct decision.