Four national surveys conducted in June asked a presidential vote preference question that included independent Ralph Nader and Libertarian Bob Barr as choices. Averaging those polls shows Nader as the choice of 4 percent of voters and Barr as the choice of 3 percent. Could these two candidates really win that much support in November?
Let’s start with more detail on those surveys. Live interviewers asked two vote preference questions, one offering only Barack Obama and John McCain as choices and the second offering all four candidates. With Nader and Barr included, support for Obama and McCain dropped by 2.5 percentage points each, on average. Nader’s support ranged from 4 percent to 6 percent, Barr’s from 2 percent to 3 percent.
Now for some historical perspective: During June 2004, according to the RealClearPolitics compilation, Ralph Nader earned the support of an average of 4.5 percent of voters on 19 national polls that asked a question including him as a choice along with George W. Bush and John Kerry.
Bush led by an average of 1 percentage point (45 percent to 44 percent) with Nader included. On 17 national polls fielded that month that did not include Nader among the choices, Kerry led by a point (47 percent to 46 percent).
Nader’s support on Election Day of 2000 was roughly half what polls had shown during the summer.
By November, Nader’s support had dropped off considerably in national polls. Most pollsters were by then asking a single vote preference question that included Nader and his running mate, Peter Camejo, in states where that ticket appeared on the ballot. The final RealClearPolitics average showed Bush and Dick Cheney with a 1.5-point lead over Kerry and John Edwards (50.0 percent to 48.5 percent), with Nader and Camejo receiving an average of just 1.0 percent of the vote.
But even that overstated support for the Nader-Camejo ticket. They received just 0.38 percent of the national popular vote.
The pattern was similar in 2000. Thirteen national polls conducted that June (retrieved from the Roper Center Ipoll Databank) showed Nader receiving an average of 5 percentage points, and Pat Buchanan 3 points, in matchups against Bush and Al Gore.
Nader’s support on Election Day -- 2.7 percent of the popular vote -- was roughly half what polls had shown during the summer, though obviously far better than it would be in 2004. And of course, Nader appeared to take enough votes from Gore in Florida to throw the election to Bush. Buchanan received just 0.3 percent of the popular vote.
The pattern of fading support for third-party candidates extends to those with more perceived viability than Nader, Barr and Buchanan. June polls by Gallup showed George Wallace with 16 percent of the vote in 1968, John Anderson with 22 percent in 1980 and Ross Perot with 22 percent in 1992 and 17 percent in 1996. Each fared worse on Election Day, especially Anderson in 1980 (6.6 percent) and Perot in 1996 (8.4 percent).
Why does early support tend to collapse for third-party candidates? One theory is that the lack of perceived viability eventually erodes their support. Voters might truly prefer a Nader or a Barr but ultimately decide that their vote is better used to decide between the major-party candidates.
Another theory says that the apparent support for the also-rans may be an artifact of the question order and structure. By asking about Obama and McCain first, and following with a four-way choice that includes Nader and Barr, some respondents may interpret the second question as an opportunity to offer their second choice.
A third theory suggests that some voters choose a third-party candidate in a poll as a way station for "undecided." Since many voters are torn between the major candidates, and since pollsters do not offer “undecided” as a choice, some respondents may opt for a third-party candidate as a way of avoiding the central question while satisfying the interviewer’s demand for an answer.
Unfortunately, we lack clear-cut answers. History tells us to be skeptical of summer poll support for third-party candidates, but the reality of current voter preference is a mystery whose answer may well vary with the choices voters have available to them.