Long-term contracts for electricity can counter market power and reduce prices in short-term markets. If electricity retailers face competition, however, companies signing long-term contracts are exposed to the risk that a fall in short-term prices would allow rivals to buy on the spot market and undercut them. Could this lead to less contracting and higher prices? This paper combines a model of electricity retailing and a Cournot model of competition in the wholesale markets to estimate the size of this effect, and finds that it could raise wholesale prices by two or three percent.