优蜜传媒

GALLUP NEWS SERVICE

PRINCETON, NJ -- Two significant milestones in this year's campaign are being reached within days of each other -- the end of the Republican convention and Labor Day, the unofficial start of the fall campaign period. Both provide important reads on President George W. Bush's election prospects. Post-convention polling will measure whether a "bounce" in voter support creates some distance between Bush and his challenger, Democratic presidential candidate John Kerry. Bush's standing versus Kerry on Labor Day could also define his re-election prospects, as historical 优蜜传媒polling shows that candidates who are substantially ahead at this point usually go on to win. 

While 优蜜传媒cannot answer questions about what the ballot will look like on Labor Day until new CNN/USA Today/优蜜传媒poll results are released after the holiday, Gallup's historical polling record provides context for what the post-convention results might mean for Bush's re-election prospects.

The Bounce

An analysis of past polling in election years documents that a party's ticket typically enjoys a "bounce" in the horse race polls after its convention. The fact that these convention bounces occur has become an expected part of the political drama of presidential campaigns. Journalists and pundits discuss the bounces at great length.

However, Kerry did not receive a bounce following his party's convention in Boston earlier this summer. Attention now focuses on whether Bush will get a bounce of his own, and if so, how large it will be.

This discussion of the expected size of a convention bounce is based on historical comparisons, which are not always straightforward. By definition, bounces have a starting and an ending point. The calculation of the starting point is a little murky given that there are weeks leading up to a convention that include convention preliminaries such as the selection of a vice presidential candidate. Nevertheless, for our purposes, we can say that the pre-convention starting point is the last full nationwide poll taken before the convention begins. The calculation of the ending point is straightforward: the first nationwide poll taken after the convention ends.

The bounce, thus, is the difference in the candidate's vote percentage in the last nationwide poll conducted before the convention and the first nationwide poll conducted after his party's convention.

Gallup's polling history allows us to examine the bounces that have occurred for both major-party candidates in each election since 1964.

The highest post-convention bounce in Gallup's records is 16 points, recorded for Bill Clinton in 1992. Support for Clinton grew from 40% just before the Democratic convention, to 56% just after it. This turned Clinton's 8-point deficit against George Bush into a 22-point lead -- yielding a dramatic 30-point swing in the race. The 1992 situation was unusual, however, in that third-party challenger Ross Perot dropped out just as the Democratic convention was ending, creating a powerful political vacuum that Clinton was able to fill. 

The lowest bounce recorded is that seen for Kerry following this year's Democratic convention. Support for Kerry actually declined by one point among registered voters (and two points among likely voters) over the course of the convention -- a "negative bounce." Kerry is not the first candidate to experience no boon from his convention. George McGovern saw no change in support for his candidacy spanning the Democratic convention in 1972. Other candidates -- Hubert Humphrey in 1968, Lyndon Johnson in 1964, and Bob Dole in 1996 -- each received very small bounces of no more than three points (although Dole did get an eight-point surge in support after naming Jack Kemp as his vice presidential running mate prior to the convention).

Altogether, however, the average convention bounce in candidate support among registered voters across all conventions from 1964 through 2000 is 6.3 points. Excluding 1992 (because of Clinton's anomalous convention bounce), the average convention bounce, historically, is 5.8 points.

Factors That Affect the Bounce

Not all conventions are created equal, of course. Idiosyncratic circumstances make a big difference in the degree to which candidates can benefit from their parties' labors at their conventions.

There are, however, several structural dimensions that theoretically could affect the size of a convention bounce:

1. The order in which the conventions occur

Looking at all bounces between 1964 and 2000, there appears, at first, to be a real advantage in terms of a ticket's bounce when that party's convention comes first. First convention bounces average 7.0 points, while second convention bounces average 5.5 points. But that advantage is significantly diminished when 1992 (with Clinton's extraordinary 16-point first convention bounce) is removed from the analysis. Excluding 1992, the average first convention has produced a 6.0-point bounce, compared with 5.6 points for second conventions.

2. Whether the party holding the convention is currently in the White House

Including 1992 in the calculations, challengers look like they have a significant edge over incumbents (7.1 points for challengers vs. 5.5 points for incumbents). Excluding 1992, however, the average convention bounce for challenger candidates drops to 5.7 points, essentially the same as the 5.7 bounce points that incumbents received. 

3. The party effect

Historically (but excluding 1992), Republican and Democratic candidates have received comparable bounces, averaging 5.7 points and 5.9 points, respectively. When including 1992, the Democrats surge ahead on this comparison, leading Republicans by more than a full point: 6.9 points vs. 5.6 points.

So How High of a Bounce Will Bush Get?

Based solely on history, the Bush-Cheney ticket could expect to gain five to six points among registered voters after this week's convention. That would result in a 52% to 53% support level for Bush among registered voters, up from 47% in the pre-convention poll. 

However, the results from Gallup's post-Democratic convention poll showed that history might not apply in 2004, a year in which the electorate was activated long before the conventions (usually the conventions serve to activate voters), and a year in which relatively small proportions of undecided and swing voters are available to the two presidential tickets. Also, the post-Democratic convention poll suggested that the Democratic convention might have helped energize Republican voters. It is unclear whether the Republican convention could have a similar paradoxical effect on Democrats, or if Republicans will be activated, as is typically the case. 

Labor Day Standing

The late date of the Republican convention pushes it into September, the first time a convention has spilled over into that month. That means Bush's post-convention standing will be the same as his Labor Day standing. Typically, Labor Day is viewed as the start of the fall campaign.

Since 1936 there have been 17 presidential elections. Of these, the final election results have ended up being fairly lopsided in 1952, 1956, 1964, 1972, 1984, and 1996. The prevailing candidates were well ahead on Labor Day in the polls these years, as they were for most of the year.

Of the remaining 11 more hotly contested elections where the margin between the candidates in the final election outcome was not as wide, in seven cases (1936, 1940, 1944, 1968, 1976, 1988, and 1992), the winner was ahead on Labor Day. In two cases, the eventual winner was behind his opponent (1948 and 1980). And in the two other instances, the winner was essentially tied with his opponent (1960 and 2000). The 2000 election (where Bush trailed Gore by three points after Labor Day) could be interpreted either way, depending on whether "winner" is defined as the candidate with the most popular votes or the most electoral votes.

Out of the 17 elections since 1936, 12 included an incumbent seeking re-election -- as Bush is now. Of the nine successful incumbents, all but one (Truman) were ahead as of Labor Day. Of the three unsuccessful incumbents, only one (Jimmy Carter in 1980) was ahead on Labor Day, while the other two (Ford in 1976 and Bush in 1992) were behind. While both Ford and Bush managed to shrink their Labor Day deficits by Election Day, neither managed to win. 

Clearly, the odds favor Bush's re-election if he can establish a lead over Kerry on Labor Day, and the odds obviously become greater the larger Bush's lead over Kerry is at that point. But it is important to note that in more competitive elections such as the one this year, the candidates' standing on Labor Day, alone, is not necessarily strongly correlated with the outcome. In elections in which the Labor Day gap was five points or fewer, the leading candidate prevailed only twice (in 1936 and 1940) and lost three times (in 1960, 1980, and 2000). It is important to note that in 1960 and 2000, the leads were not outside the polls' margins of error, so the candidates could be considered to have been tied on Labor Day.   

This table details the standings of the candidates on Labor Day. Winning candidates are highlighted in bold letters. 

 

	Sample	Republican candidate	Democratic candidate	Third-party candidate	Third-party candidate
2000 Sep 4		Bush	Gore	Nader	Buchanan
2000 Sep 4-6	LV	44%	47	3	*
2000 Sep 4-6	RV	41%	47	3	1
1996 Sep 2		Dole	Clinton	Perot
1996 2-4	LV	36%	53	5
1996 2-4	RV	35%	54	5
1992 Sep 7		Bush	Clinton
1992 Sep 11-15	RV	42%	51
1988 Sep 5		Bush	Dukakis
1988 Sep 9-11	RV	49%	41
1984 Sep 3		Reagan	Mondale
1984 Sep 7-9	RV	55%	44
1980 Sep 1		Reagan	Carter	Anderson
1980 Sep 12-15	RV	37%	41	15
1976 Sep 6		Ford	Carter	McCarthy
1976 Sep 24-26	RV	40%	51	4
1972 Sep 4		Nixon	McGovern
1972 Sep 22-25	RV	61%	33
1968 Sep 2		Nixon	Humphrey	Wallace
1968 Sep 3-7	RV	43%	31	19
1964 Sep 7		Goldwater	Johnson
1964 Sep 18-23	RV	32%	62
1960 Sep 4		Nixon	Kennedy
1960 Sep 9-14	RV	47%	46
1956 Sep 3		Eisenhower	Stevenson
1956 Sep 9-14	RV	52%	41
1952 Sep 1		Eisenhower	Stevenson
1952 Sep 6-11	RV	56%	40
1948 Sep 6		Dewey	Truman	Wallace	Thurmond
1948 Sep 10-15	NA	47%	39	3	2
1944 Sep 4		Dewey	Roosevelt
1944 Sep 8-13	NA	45%	50
1940 Sep 2		Willkie	Roosevelt
1940 Sep 5-10	NA	40%	49
1936 Sep 7		Landon	Roosevelt	Lemke	Thomas
1936 Sep 7-12	NA	45%	49	5	1

Bottom Line

The next CNN/USA Today/优蜜传媒poll will provide the data needed to get a better understanding of Bush's re-election prospects as the campaign gets into full swing. It is not known right now how Bush will fare after the Republican convention. Although historical evidence suggests that Bush should gain a lead over Kerry after the convention, the Democratic convention in late July suggested that this year may be an anomaly. Everything else being equal, if one or the other candidate is substantially ahead of his opponent on Labor Day, history suggests he stands a pretty good chance of being elected in November.