Conventions Usually Give Candidates A Boost In The Polls. What About This Time?

With the parties jettisoning tradition amid a national pandemic, the "convention bounce" could be another casualty.

This year’s political conventions are throwing tradition by the wayside. With the Democratic convention going digital, and the GOP’s set to be significantly pared down, both events are jettisoning much of their usual pageantry, buzz and hordes of on-scene reporters. What’s less clear is whether that’ll also dampen a subsequent tradition: the post-convention bounce.

Presidential-year conventions, which give parties a highly publicized, largely scripted platform to rally around their chosen nominees, usually give candidates a boost in the polls. With many voters just beginning to tune in to the election, the conventions are an opportunity to introduce the candidates, their platforms and their running mates.

That tends to have a measurable effect on the polls. On average, candidates between 1964 and 1992 saw about a 6-point “convention bounce,” according to Gallup’s polling, with those in more recent years seeing a more modest bump, just shy of 4 points. (General election debates, by contrast, tend to have less of an effect.)

It’s unclear whether largely digital conventions are likely to have the same effect. 

“It feels to me that the conventions will be much less in terms of a ‘reset’ for the campaign,” Rick Klein, ABC News’ political director, told U.S News & World Report. “The storylines and color that can make conventions compelling to cover – it’s hard to see them materializing this year.”

On the other hand, with other campaigning also pared to a minimum by the pandemic, and an unusually high share of the public bored at home, the events could still attract significant attention.

A banner of the Democratic National Convention hangs outside the Chase Center in Wilmington, Delaware, on Aug. 17.
A banner of the Democratic National Convention hangs outside the Chase Center in Wilmington, Delaware, on Aug. 17.

“It’s hard to say what we should expect” to see in the polling after the convention, Tom Holbrook, a political scientist at the University of Wisconsin-Milwaukee, wrote. “On one hand, the well-choreographed convention floor ‘show’ will be missing, potentially robbing ... both Biden and Trump of whatever benefits there are from the spectacle nature of these sorts of events.  At the same time, the candidates are still the beneficiaries of four straight days during which they probably will dominate media coverage, including two-hours of prime-time television coverage each night of the convention.” 

Even if this year’s conventions looked more like business as usual, their effects on the race might be limited. For one thing, some analysts have expressed skepticism about the phenomenon of “bounces” in general. They suggest that some of the difference is due less to shifting opinions than to a temporary shift in how likely Republicans and Democrats are to take surveys.

This represents a form of an effect called differential non-response, in which partisans are more apt to answer polls following an energizing event like a convention (or vice versa, less likely to respond in the wake of bad news for the side they support). In 2012, for instance, internal polling for Barack Obama’s campaign, controlling for the partisan composition of the sample, registered far less of a convention bounce than some public polls at the time.

Then, there’s that decline in the average size of a convention bounce. Increasingly compressed scheduling ― this year, there are just four days between the end of the Democratic convention and the start of the Republican one ― may be helping to limit the events’ potential impact. Voters are also tuning in to election news earlier. And responses to the conventions have grown increasingly partisan in recent years, meaning there may be fewer possibilities for persuasion.

“Conventions may no longer serve to introduce the nominees to Americans,” Gallup’s Jeffrey M. Jones wrote in 2012. “Rather, Americans probably already have a good sense of who the nominees are and what they would do if elected president ... This could particularly be true in years in which incumbents are running for re-election, and voters’ choices may boil down to whether they want to re-elect the president as opposed to choosing which of two candidates they would prefer to be president.” 

That’s precisely the case in 2020: Both Donald Trump and Joe Biden are well-known to the public, interest in the election is already high, and much of the electorate views the race as primarily a referendum on Trump.

“Maybe there’s less to be gained from the conventions than was usually the case in the past,” said Christopher Wlezien, a political scientist at the University of Texas at Austin. Often, “the conventions get people to take stock” of the current political situation, including their views of the incumbent president, he said. “But people have already taken stock. There’s not much stock-taking left to do.”