We analyze a game of electoral campaign between a representative voter and two candidates in which each of them has to decide the amount of time she devotes to an issue. In order to study the communication strategies of candidates on issues during an electoral campaign, we assume that the voter has priors about candidates' competence on issues and preferences for issues. Candidates are endowed with fixed level of competence on each issue and may affect voter's priors by discussing the issues. The level of time spending by candidates on an issue affects the voter in two ways. First, the more candidates spend time on an issue, the more this issue becomes salient in voters' mind. Second, the time a candidate devotes to an issue increases the precision of the information he sends to voters about his true issue-competence. The voter updates his beliefs according to the information he received from candidates on each issue. Candidates tend to talk about an issue as soon as their true issue-competence is better than the voter's priors ; the more competent candidate stressing more the issue, the time devoted by the less competent candidate increasing with his competence and his capacity to induce a competence update in voters' mind stronger than the increase of the weight voters give to the issue. This result differs from the literature which generally justifies that two candidates have never interest to talk about the same issue. We determine also conditions under which only one candidate talks about an issue as well as conditions under which candidates remain silent on an issue.
By extending the analysis from one to several issues, and by taking into account a global time constraint, the probability of "dialogue" decreases as candidates discuss more issues on which they are more competent than what voters a priori believe and than their opponent.