A contested convention happens when no presidential candidate arrives at the party’s national convention with a majority of delegates. The convention holds a first ballot anyway, and if nobody wins, delegates are freed to vote for anyone on later ballots. Voting continues, with deal-making between rounds, until one candidate wins a majority.
Neither major party has needed more than one ballot to pick a nominee since 1952, because the modern primary calendar almost always produces a clear winner. But both parties’ 2028 fields are open, and a crowded race is the one scenario where a contested convention becomes realistic.
How do delegates normally pick the nominee? #
When you vote in a presidential primary or caucus, you’re really helping choose delegates who will vote at the national convention. Each party writes its own rules for how many delegates each state gets and how they’re awarded.
- Democrats award pledged delegates proportionally. A candidate who wins at least 15% in a state or district gets a share of its delegates roughly matching their share of the vote. Our guide to how pledged delegates are allocated has the details.
- Republicans let states choose. Many use winner-take-all or winner-take-most rules, especially later in the calendar, which helps a front-runner build a majority quickly.
To be nominated, a candidate needs a majority of delegates voting at the convention. In most years someone clinches that number in the spring, and the convention is a formality.
What happens step by step at a contested convention? #
1. The fight starts at the Rules Committee #
Before any voting, the convention adopts its rules. In a contested year, the Rules Committee becomes the first battleground. Campaigns lobby to change thresholds, adjust how delegates are bound or challenge the seating of rival delegations, since each change can move the math.
2. The first ballot #
The roll call goes state by state. Most delegates vote for the candidate they were awarded to in their state’s primary or caucus. Democratic superdelegates can’t vote on the first ballot unless the result is already decided, a rule adopted in 2018. Our explainer on superdelegates covers it. If someone reaches a majority, it’s over.
3. Later ballots free more delegates #
If the first ballot fails, the convention votes again. Party and state rules decide when each delegate is released. Many Republican delegates are freed after the first ballot and others after the second or third. Democratic rules have never strictly bound pledged delegates. They’re asked to “in all good conscience reflect the sentiments” of the voters who elected them, which in practice keeps them loyal on the first ballot. After that, superdelegates join the voting too.
4. Deals between ballots #
Once delegates can move, campaigns and party leaders work the floor and the hotel suites. Candidates can offer the vice-presidential slot, cabinet posts or platform changes in exchange for a rival’s support. A trailing candidate might drop out and release their delegates to someone else. Voting continues until one candidate has a majority.
Contested vs. brokered convention: is there a difference? #
The terms get used interchangeably, but there’s a useful distinction.
| Contested convention | Brokered convention | |
|---|---|---|
| Definition | No candidate has a majority of delegates going in | A contested convention settled by party leaders steering blocs of delegates |
| Who has power | Individual delegates, voting ballot by ballot | A small group of leaders and power brokers |
| How likely today | Possible in a crowded, split field | Rare, since party bosses no longer control large delegate blocs |
Brokered conventions were common in the era of party machines, when a state boss could deliver a delegation. Today’s delegates are chosen through primaries and are more loyal to candidates than to party leaders, so a contested convention would probably play out more openly.
When did conventions last go to multiple ballots? #
- 1924 Democratic convention: 103 ballots. Delegates split between William McAdoo and Al Smith for more than two weeks before settling on John W. Davis, who lost the general election badly.
- 1948 Republican convention: 3 ballots. Thomas Dewey won on the third ballot, the last multi-ballot Republican convention.
- 1952 Democratic convention: 3 ballots. Adlai Stevenson, who hadn’t campaigned in the primaries, won on the third ballot. It remains the last time either major party needed more than one ballot.
- 1976 Republican convention: 1 ballot, but close. President Gerald Ford arrived just short of a majority, with Ronald Reagan close behind. Ford won over enough uncommitted delegates to prevail on the first ballot, 1,187 to 1,070.
Why are contested conventions so rare now? #
After the 1968 Democratic convention in Chicago nominated Hubert Humphrey without his having run in the primaries, both parties moved to the modern primary system. Several features of that system prevent deadlocks:
- Front-loading. Many states vote early, including on Super Tuesday, so trailing candidates run short of money and drop out quickly. See front-loading in presidential primaries.
- Winner-take-all rules in many Republican contests let a leader pull away.
- Party pressure. Parties fear the damage of a public floor fight, and leaders push trailing candidates to exit and endorse the front-runner.
The one pattern that could beat those forces is a field of three or more candidates who each keep winning enough delegates to stay in, especially under the Democrats’ proportional rules.
How can you tell if 2028 is heading toward a contested convention? #
Watch whether one candidate’s support pulls away from the rest after the early states. Election Tracker’s 2028 Primary tab shows national polls of both parties’ fields, each with a polling average and a trend line, and a candidate has to appear in enough polls before being averaged. If three candidates’ lines stay bunched together into the spring of 2028, the delegate math gets interesting. Its Market Sentiment tab also shows read-only Polymarket prices on each party’s nominee, labelled as trader sentiment. Our guide to when the 2028 primaries begin covers the calendar.
Frequently asked questions #
Can someone who didn’t run in the primaries be nominated? #
Yes, in theory. Once delegates are freed, they can vote for any eligible person. Stevenson in 1952 is the closest modern precedent. Today a dark-horse candidate would still need to meet any rules the convention sets for being formally placed in nomination.
How long would a contested convention last? #
Until someone wins a majority. That could take a few ballots over one evening or, as in 1924, more than two weeks. Today’s media pressure and convention logistics would push parties to settle within a few days.
Do superdelegates vote on the first ballot? #
Not if their votes could change the outcome. Since 2018, Democratic superdelegates can vote on the first ballot only when a candidate has already clinched a majority of pledged delegates. They vote on every ballot after the first.
Does a contested convention hurt a party in November? #
It often has. Floor fights expose divisions, leave less time to unite the party and give the other side material. The 1924 Democrats and the 1976 Republicans both lost the general election, though many factors were involved each time.