What is a brokered convention?

A brokered or contested convention happens when the primary process ends without any single candidate securing a majority of delegates. When the convention opens, no one can win on the first ballot, so delegates are freed (in whole or in part) to vote for other candidates in subsequent rounds. The outcome is decided by negotiation, horse-trading, and coalition-building on the convention floor.

This was common before the modern primary system took hold in the 1970s. The 1924 Democratic Convention famously required 103 ballots before choosing a nominee. Since primary elections became the dominant path to delegates, brokered conventions have been rare - no major-party convention since 1952 has gone beyond one ballot.

A brokered convention could occur in 2028 if the primary season produces a large, fragmented field with no dominant candidate, or if the leading candidate suffers a late collapse. It can also result from unusual party rules or a candidate dying or withdrawing after winning delegates.

In a brokered convention, superdelegates (on the Democratic side) and freed pledged delegates become power brokers. Campaigns negotiate and attempt to build delegate coalitions to reach the majority threshold, sometimes leading to a nominee who was not the primary frontrunner.