By Jonathan Bernstein
It was treated as big news earlier this week when Meg Whitman, the chief executive of Hewlett Packard Enterprise, along with a handful of other Republican figures, announced they would vote for Hillary Clinton. Whitman, who was a GOP candidate for governor of California in 2010, is a billionaire and will be raising money for Clinton. The other Republicans decamping are Richard Hanna, a New York congressman who is retiring, and at least three campaign operatives.
Some pundits were quick to ridicule the notion that such defections will affect any actual voters.
It's true that few people will wonder why Sally Bradshaw, a former Jeb Bush adviser, is switching to the Democratic ticket, for example, let alone be swayed by her decision. Indeed, most voters would say they don't care about endorsements from even the most high-profile members of their party. Some people will claim they dislike these leaders anyway.
Yet dismissing the importance of the endorsements is wrong.
In a normal election when both parties are united behind their nominee, voters will hear one message for months: that people like themselves, including the politicians they like, are supporting one candidate, while people they normally dislike or disagree with are backing the other one. Whether voters consider themselves partisans or not, that message pushes them in the "correct" direction -- to the candidate of the party they normally support.
Conventions are especially powerful in sending such signals because they dominate the news for a few days at least, drowning out the voices of the opposing party. Even after the convention, that message can be strong -- if the party is united, that is.
The muddier things are, however, the less likely voters will be pushed in the "correct" direction.
This is probably a big part of what has given Clinton a solid lead in the polls right now. The Democrats are united and sound united, while Republicans clearly are not.
When something goes wrong for Clinton, most highly visible Democrats will speak out in support or keep their mouths shut. By contrast, when something goes wrong for Donald Trump, Republican responses are all over the place, with many condemning whatever it is he said.
And the media's preference for man-bites-dog over dog-bites-man stories means that the news about a Republican operative endorsing Clinton will receive far more coverage than dozens of Republican elected officials endorsing Trump.
This provides constant cues for voters. There may be no effect on those who decided months ago to support Trump or Clinton. But many voters don't pay much attention until the campaign's final weeks. And even though most voters are (in normal elections) predictably partisan in the end, many of them don't arrive at their destination by stating their party preference and automatically choosing their party's candidate.
Instead, a lot of partisanship is activated by the events and rhetoric of the campaign. If the campaign doesn't provide the push, then many voters may get lost on the way to where they "should" be heading.
Jonathan Bernstein is a Bloomberg View columnist covering U.S. politics.
For more columns from Bloomberg View, visit http://www.bloomberg.com/view.