PRINCETON, NJ -- The lead in the Republican nomination race has thus far changed seven times since May in Gallup polling. Mitt Romney, Rick Perry, Herman Cain, and Newt Gingrich each held the top spot at various points in 2011, with Romney's standing rising and falling as other candidates surged and faded.
Mike Huckabee led the Republican field, or tied Romney and Sarah Palin for the lead, in Gallup polls at the start of the year; however Huckabee and Palin ultimately declined to run.
The volatility in Republican preferences in 2011 most closely resembles changes in Democrats' preferences in 2003 when Joe Lieberman, John Kerry, Tom Daschle (not an announced candidate), Dick Gephardt, Howard Dean, and Wesley Clark each had their turn as front-runner, before Kerry took command of the race at the start of the primaries in 2004. The lead changed hands nine times in Gallup polling throughout 2003.
This is the first presidential election since 1964 that the Republican Party has had so many candidates in serious contention for a nomination, although many of the shifts in national Republican preferences in the 1964 race occurred after the primaries began, rather than in the year leading up to it.
Nelson Rockefeller and Barry Goldwater were the only Republican front-runners in Gallup polling in 1963. Then, during the primary season in 1964, Richard Nixon, Henry Cabot Lodge, and William Scranton all emerged in the lead or tied for the lead, before Goldwater won the nomination at a hard fought convention.
The race for the 1988 Democratic nomination provides another example of high uncertainty about the party front-runner in the year prior to the start of the primaries. In 1987, the lead shifted between Gary Hart and Jesse Jackson. Hart also held the lead throughout January 1988 before Michael Dukakis emerged as the strong front-runner later in the season.
Tuesday's Iowa caucuses mark the close of the preliminary phase of the 2012 Republican nomination contest and the start of actual voting that could result in additional national preference swings before the nomination is settled. Historical comparisons of primaries can be problematic given differences in the number of candidates and number of poll conducted each election. It seems clear, however, that this phase of the 2012 Republican nomination process has been the most volatile for the GOP since the advent of polling. Still, the Republicans' four front-runners and seven switches in the lead seen in Gallup polling since May fall short of the Democrats' six front-runners (excluding Daschle) and nine switches of 2003.
It remains to be seen whether the entire 2012 Republican nomination, from the preliminary phase through the primaries, winds up significantly different from 1964 in terms of volatility. Should Romney maintain his current edge from now through the end of the primaries in June, the total number of shifts in front-runners between the two elections will be about the same.