Populists are often anti-elitist and advocate for popular will over expertise. We show that these two populist characteristics are responses to mainstream parties leaving behind the majority of voters, the common people. Our model highlights two forces behind electoral success: numbers, which favor the common people, and knowledge, which favors the elite. Electoral competition may lead parties to cater to the elite. We identify conditions under which an elite bias encourages entry with an anti-elite platform. Finally, we identify conditions under which parties follow the common people's opinion when that group would benefit from parties relying on experts.