This talk presents a model of bipartisan elections where voters are exposed to two forces: local homophilic interactions and external influence from two political campaigns. The model is mathematically equivalent to the random field Ising model with a bimodal field, and it predicts complex behavior among electoral candidates. Beyond a critical campaign spending threshold, the system undergoes a phase transition to a highly polarized state, where homophilic influence becomes negligible and election outcomes mirror the proportion of voters aligned with each campaign, independent of total spending. Calibrating the model with historical data from US House elections between 1980 and 2020, we find that the critical campaign spending is approximately $ 1.8 million USD. Campaigns exceeding this threshold increased in 2018 and 2020, suggesting a boost in political polarization.