Corresponding author: Piergiorgio Carapella
We analyse how candidates engage in campaign advertising in a proportional (PR) system with preference votes. Candidates are policy motivated and they compete in a two seats district. We compare our model to other setups, single district and closed list, and we show that in open lists intraparty competition drives candidate to spend more on campaign activities. We then test our model using an original dataset of Lombardy's Regional Elections. Campaign spending positively depends on intraparty competition, the candidate position in the list and on the vote share of the party, moreover, in closed lists the total level of spending is lower.