Multiparty EMBs comprise a mixture of political party nominees as EMB members. The legal framework may entitle all political parties contesting an election to be represented on the EMB, or representation may be restricted by some threshold – for example, to those represented in the legislature or with more than a specified proportion of members in the legislature. In Venezuela in the mid 1990s, the larger parties each had their own representative, while smaller parties of the left and right were represented collectively.

Political party-based appointment often implies that EMB members are serving on the EMB as political party representatives or agents and, as well as impartially managing electoral processes, serve to ensure that their nominating political parties’ interests are protected. While each individual member is seen from outside as partisan, each is also ensuring that the others do not take partisan advantage – so the EMB can nonetheless credibly be perceived as an impartial body. Political party-based members often hold office for a fixed term and cannot be dismissed except for cause, such as a breach of their duties, or upon their withdrawal by their nominating authority. Allowing parties to replace their representatives at their own discretion is potentially very disruptive of the work of the EMB.

In some countries, however, political party nominees to the EMB are eminent persons who are required to maintain high standards of impartiality and professionalism, and thus they do not serve as political party representatives on the EMB, although in some cases it has not been easy for even these eminent political party nominees to be completely impartial.

Many countries, especially those that experienced difficult transitions from authoritarian rule to multiparty democracy, have chosen multiparty-based or partisan EMBs. In such societies, public servants are likely to have been largely discredited as electoral policy makers due to a history of being agents of the authoritarian former ruling party or military regime. Additionally, the fight against authoritarianism may have polarized society to the extent that it is difficult to find public figures widely accepted as ‘independent’ to serve on the EMB for a transitional election. Many of the countries of Central and Eastern Europe adopted multiparty-based EMBs during their transitions.

Many electoral analysts believe that having political party representatives on the EMB engenders consensus among actors in the electoral contest and contributes to enhanced transparency, all of which lead to improved confidence in the electoral process. Voters may feel more encouraged to participate in elections if their political party leaders are playing an active role in the electoral process, specifically through representation on the EMB.

On the other hand, a political party-based EMB can put at risk or cripple decision-making, especially in situations where their critical interests are at stake. The presence of politicians on the EMB may undermine confidentiality in matters such as the security of balloting materials. Multiparty-based EMBs also tend to generate dissatisfaction, especially among minority parties which might be excluded from sitting on the EMB either because they are not represented in the legislature or because they did not participate in the negotiation leading to the initial appointments of EMB members.