Electoral pledges and their fulfilment cover an essential role in democratic systems and are highly relevant to the concept of political representation. Most studies define pledges as sentences that both show a commitment and are objectively “testable”. However, little attention has been paid to variations in the strength of commitments and consequently to the non-testable “soft” pledges: those that are ambiguous, vague and very general. Recent studies have shown how ambiguity of party platforms can be a rewarding electoral strategy and can be strategically used to balance the demands of the general electorate and party activists. We argue that the role of intra-party politics can be equally important in explaining the sources of ambiguity: adopting vague stances might result in fact from a failed compromise or an attempt to lessen conflict among factions within the party. This paper aims to test this argument by exploring how the degree of parties’ ideological heterogeneity influences the strength of commitments. The hypothesis is tested on a dataset including about 200 parties across 23 countries and 30 elections. Party ideological heterogeneity is operationalised through individual policy positions from elite survey data that enable analysis of elite-level party ideology and heterogeneity. To capture the strength of commitments, we focus on the degree of specificity of the electoral pledges included in party manifestos. Specificity is estimated using Speciteller, a text-analysis tool designed to detect ambiguity by scoring sentences from most general to most specific.