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The momentum equation

In physics, momentum is the product of velocity and mass. In politics, it's much harder to calculate -- but it may be growing in importance.

Candidates, pollsters and pundits all agree that the way next year's presidential primary schedule is shaping up, with the possibility that as many as 19 states will vote on Feb. 5, the process is going to change, and dramatically. California, New Jersey, Texas, and Florida -- states whose primaries have in recent decades taken place after the front-runner has already locked up the nomination -- are moving their primaries up in an attempt to make their votes matter. As a result, instead of a drama that unfolds gradually, over the course of several months, nearly half the party delegates could be decided within a few weeks of the start of the primary season.

And yet, as many race handicappers concede, it's hard to predict exactly how the new schedule will affect the chances of the various candidates and the importance of the different state primaries. Will it augment or diminish the importance of the "first in the nation" New Hampshire primary and Iowa caucuses? Will it help or hurt lesser-known candidates like Democrat Bill Richardson or Republican Sam Brownback? Is it likely the race will be decided earlier, or will an inconclusive result on Feb. 5 mean uncertainty all the way to the party conventions? On these questions, prognosticators are all over the map.

There is, however, a word that comes up again and again in these predictions, and, for that matter, in any discussion of the primaries: "momentum." The influential election analyst Charlie Cook wrote earlier this month that turning Feb. 5 into what he called "the Powerball Primary" meant that, for candidates, "having plenty of money and momentum before that date becomes even more important."

"We've got to build the momentum," said John McCain a week and a half ago as he boarded his bus, the "Straight Talk Express," for a two-day tour of Iowa meant to boost his flagging poll numbers.

Indeed, many analysts worry that the new, front-loaded primary season will be particularly momentum-prone. Without much time between the start of the primaries and Feb. 5, a candidate could ride the momentum from an early victory right through to a commanding lead in delegates before prospective voters have had a chance to see him or her tested over the course of a long campaign.

All of which suggests that politicial momentum is a force to be reckoned with, managed, somehow controlled. But this assumes that we know what it is and how to account for it. It's one thing to figure out the momentum of a moving car or a baseball, but what does it mean in an election?

In part, it's simply a narrative trope, a way for commentators and journalists to impose an easy story line on the inherent shifts and swings of a campaign. In the months before the 2004 primary season, reporters axiomatically described Democratic front-runner Howard Dean as having a lot of momentum -- until he lost the Iowa caucuses, at which point he was judged, sensibly enough, to have lost it.

But especially in primary season, when early results tend to have a bearing on later ones, momentum does seem to be a very real force. As William Mayer, a political scientist at Northeastern University who has written extensively on the nomination process, points out, "It's not uncommon to see a candidate gain 15 to 20 points in the polls after they win in Iowa and New Hampshire."

How exactly to define and account for momentum has intrigued scholars of voting behavior for decades. So far, though, the definition remains sketchy. According to Andy Smith, director of the University of New Hampshire's Survey Center, "it's very difficult for political scientists to come up with a working definition and a way to measure momentum." And while that hasn't stopped a few scholars from trying, the evolving and stubbornly chaotic nature of the primary process has made the task that much harder.

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The simplest explanation for electoral momentum is that people like to vote for winners. "There are a lot of people out there who don't follow politics all the time," says Michael McDonald, a political scientist at George Mason University. When a candidate wins an early primary, "that's a signal that this might be a candidate you need to look at."

This effect, many analysts say, is fed by the press coverage of primaries. As Mark Blumenthal, a former Democratic pollster and now editor and publisher of the website, puts it, "so much of the coverage is about the horse race aspects of the campaign: who's winning, who's losing, and perfectly reasonable voters can't help but make inferences from that about the competence of the candidates."

A study by Stephen Farnsworth of the University of Mary Washington and S. Robert Lichter of George Mason University's Center for Media and Public Affairs showed a sharp shift in the tone of the network news coverage of Dean and Kerry after the 2004 Iowa caucuses and New Hampshire primaries: Newscasts dealing with Dean began to fill up with negative statements about him, and Kerry coverage became distinctly more positive.

And then there's the money. Donors, perhaps even more than voters, don't want to back a loser. It's a more recent phenomenon, says Mayer, "but one of the most powerful things you get out of doing well in the early going is a big infusion of funds."

But while there's broad agreement that money and coverage matter when a candidate is trying to build momentum, getting much more specific than that has been difficult. Part of the problem is that there still aren't that many data points. Primaries only emerged as an important part of the nominating process in the 1960s. Before then, when party nominees were chosen for the most part by insiders at the national convention, campaign momentum didn't have much meaning.

Even after the birth of the current primary system, the prevailing wisdom was that, for big states at least, being later in the schedule carried distinct advantages. According to Smith, the fact that California's primary came late only added to the state's importance. "It used to be that California's primary got a tremendous amount of attention. That was the big kahuna." Because California had so many delegates, candidates could make up for early losses with a win there, and as a result, they lavished attention on the state, often at the expense of early primaries.

In large part, that changed in 1976 with Jimmy Carter's presidential campaign. Before the primaries, Carter was largely unknown outside his native Georgia. But he focused almost all of his energy and resources on early primary states, using his surprise victories there to create a national profile for himself.

As Larry Bartels, a political scientist and specialist in voting behavior at Princeton University, wrote in his 1988 book "Presidential Primaries and the Dynamics of Public Choice," Carter's campaign was the first to show that the key to success "was not to enter the campaign with a broad coalition of political support, but to rely on the dynamics of the campaign itself, particularly its earliest public phases, to generate that support."

In 1980, George H.W. Bush modeled his primary campaign on Carter's, even going so far as to coin the phrase "Big Mo" to describe the electoral tail wind he expected from his victory in the Iowa caucuses. In reality, his Mo was negligible: he lost badly to Ronald Reagan in the New Hampshire primary a few weeks later and dropped from contention.

As Bush's example shows, then, momentum is easy to misread and not always an unstoppable force. Democrat Gary Hart's insurgent campaign in 1984, for example, got its initial boost when the formerly obscure Colorado senator posted an unexpectedly high 16 percent in the Iowa caucuses. He went on to beat then-front-runner Walter Mondale by 10 points in New Hampshire. Still, it was Mondale who went on to win the party nomination, in large part by attacking Hart, as the two campaigned in later primary states, as a fickle lightweight with vague ideas. (In 1988, Hart's presumed front-runner standing suffered the momentum-killing blow of sexual scandal.)

Indeed, according to Farnsworth and others, commentators tend to overplay the power of momentum to lift an underdog from obscurity. "The opportunity for momentum to allow candidates to come from nowhere," says Farnsworth, "history demonstrates that that just doesn't happen."

In an article published in 2004, Mayer made a similar point, arguing that in every contested primary since 1976, it had been one of the early favorites who had gone on to win the nomination. As he now admits, though, that may not have been the year to argue against momentum: After John Kerry won the Iowa caucuses and New Hampshire primary, his support among likely Democratic voters swelled from 9 percent to 68 percent and Howard Dean never seriously threatened for the nomination.

"That was a case," Mayer concedes, "where momentum really did matter."

Drake Bennett is the staff writer for Ideas. E-mail