Should Democrats be concerned about a fight between Bernie Sanders and Hillary Clinton supporters at their party convention in Philadelphia? Should Republicans be worried about protests outside the Quicken Loans Arena?
Some research suggests that prolonged primaries do not harm the eventual nominee, or at least that the results of contested primaries are ambiguous. In addition, there is at least some indication that a competitive primary season, followed by a unifying convention, may actually produce strong autumn results for the party.
On the other hand, some evidence suggests that parties beset by a conflicted convention may underperform in the general election. In an election year characterized by turmoil and uncertainty, these issues are worth consideration.
Party conventions perform two functions in the modern campaign era. First, they serve the official function of nominating the presidential candidates. The outcome of the nomination contests this year is not seriously in doubt — barring an extraordinary turn of events, Donald Trump will be the Republican nominee, and Clinton will be the Democratic nominee.
Even if Sanders "goes all the way to the convention," Clinton will have the most pledged delegates, the most support from superdelegates, and the most "popular votes." Based on those factors, she would almost certainly win the nomination even on a "contested" first ballot. But could such a contest hurt the party?
Party conventions serve a second function in the modern era: They are a three-day advertisement for the party and its ideas. They generate sustained positive news coverage for the party and its nominee. The conventions (perhaps because of that coverage) generate a bounce in the polls that is one of the only durable changes in poll standings during the course of the general election.
A number of factors have been shown to affect the size of the convention bounce. Thomas Holbrook suggests that the convention bounce brings polling into alignment with the fundamentals of the race (which in 2016 would favor the Republicans), and that timing matters as well. The party with the first convention (again, in 2016 the Republicans) often experiences a bigger bounce, but a short time window between conventions (the contests will be separated by four days this year) can diminish the positive effect of going first.
The convention bounce seems to work mostly by reminding leaning partisans why they usually vote for their preferred party and why they should vote for its nominee. A divisive convention risks undermining positive news coverage and the increase in support for the party's candidate such coverage can produce.
The data we have on convention bounces is noisy, but a number of examples suggest that when a party underperforms its expected convention bounce, the content of the convention, and its news coverage and commentary, may play a role. Divisive conventions and negative coverage do seem to be associated with the most dramatically "underperforming" convention bounces:
- In 1968, Democrats Hubert Humphrey and Eugene McCarthy battled for party control following Robert Kennedy's assassination while protesters clashed with police outside. Headlines painted a vivid picture: "A Macabre Atmosphere Pervades the Convention"; "Garrison Convention Is a Reflection of Controversies Under Democrats"; "5,000 Troops Flown to Chicago to Avert Any Convention Trouble." Humphrey received a mere 2-point poll bounce and eventually lost to Richard Nixon in a close race.
- In 1972, Democrats, still reeling from the convention of 1968, squabbled before coalescing around George McGovern. Headlines like "Rivals Vow Fight on Floor" highlighted the lingering lack of unity. McGovern actually lost ground in post-convention polling (a rare feat), falling below 40 percent.
- In 1976, Republicans were divided between President Gerald Ford and challenger Ronald Reagan. Ford was the sitting president, but he occupied the Oval Office through uninspiring circumstances. Headlines reflected the convention's somber mood: "Ford Wins a Major Test in GOP Rules Panel Vote"; "Delegates Pessimistic for November." Ford received a lower-than-expected convention bounce and lost a close race to Carter.
- In 1984, Democrats faced a fierce headwind in the fundamentals. Analysts disagree about the magnitude of the convention bounce Walter Mondale enjoyed, crediting him with a wide range of 3 to 9 points. Headlines reflected a contentious atmosphere between Mondale, Gary Hart, and Jesse Jackson, followed by a mending of intraparty divisions at the convention: "Platform Opponents Threaten Floor Fight"; "Democrats Open With Unity Pleas"; "Hart's Last Hurrah Has Optimistic Note."
- In 2008, after a hotly contested (and sometimes rancorous) primary season, the Democrats slightly underperformed their predicted convention bounce despite Hillary Clinton's prominent endorsement of Barack Obama's candidacy: "'Barack Obama Is My Candidate'; Clinton Urges Support, Calls for Party Unity."
Divided parties have sometimes also received larger-than-expected bounces, an effect that may be related to positive narratives emerging from successful attempts to heal party divisions and achieve authentic unity.
- In 1968, Republicans Nixon, Reagan, and Nelson Rockefeller vied for ideological control of the party in the wake of Goldwater's disaster in 1964. Reagan and Rockefeller sought their own nominations ("Rocky Is 'Optimistic' On Nomination Chances"; "Reagan Steps Up Convention Drive"), then unified in a "stop Nixon" campaign as the convention opened ("GOP Presents a Picture Out of Focus"). Nixon won decisively on the first ballot, however, and was unequivocally endorsed by his rivals ("Nixon Nominated on First Ballot; Convention Makes It Unanimous on Plea by Reagan"). The party's convention bounce overperformed race fundamentals significantly.
- In 1988, Democrats faced similar divisions as in 1984, with Michael Dukakis and Jesse Jackson vying for party control. Headlines such as "Whose Convention Is It?" reflected this disunity, but Jackson sought platform concessions, not a contested convention. Party unity was achieved with a public endorsement ("Jackson Rouses Democrats With Plea for Hope, Saying 'Tonight I Salute Dukakis'"; "The Democrats, All Together Now"), and was rewarded with a 7-point bounce.
- In 1992, Democrats successfully rallied behind "Comeback Kid" Bill Clinton, and received a 16-point "unity" bounce in the polls, after a contested spring. Ross Perot also dropped out — temporarily — during the convention, probably accounting for part of the bounce. Headlines such as "Democrats Give Clinton Their Blessing; Cuomo Hails 'New Voice for New America'" and "Democrats, Emphasizing Unity, Embrace a Moderate Platform" told voters about a united party.
Any conclusions about convention effects should be made with all of the appropriate caveats. Partisan divisions that endure into the convention have had inconsistent effects on the state of the race. The number of cases to examine is small. The size of the convention bounce may be totally determined by the fundamentals of the race. The presence of Donald Trump in the race may alter all the rules of politics as we know them.
However, historical examples suggest that party divisions at the convention may be communicated in press coverage, which in turn may affect voters. If conventions affect the polls primarily by generating enthusiasm for the ticket among wavering partisans, the tone of the convention itself could affect those voters' perceptions.
Examples suggest that a unifying convention that creates a positive media narrative might lead to overperformance in the polls, but they also suggest that a dramatically divisive convention can have lasting and negative impacts. In a year when both parties remain conflicted over their nominees and over policy, it may be difficult to thread the needle between these divergent outcomes. But in a year when the results of the general election are difficult to predict, party leaders should be mindful of that goal.
Casey Dominguez is an associate professor of political science at the University of San Diego. Her research focuses on political parties, campaign finance, and the presidency.
Andrew Tirrell is an assistant professor of political science at the University of San Diego. His research focuses on environmental justice, natural resource management, sustainable development, marine policy, and the Arctic.