During most presidential campaigns, political scientists like me are constantly telling anyone who will listen that the subtleties of political messaging don't matter much. Sure, speeches, advertising, and interviews with reporters can sometimes make the difference in local, House, or even Senate and gubernatorial races. But that is because in those elections, the campaigns are often greatly mismatched in resources and political skill.
There is a lot of evidence that campaign communication has diminishing marginal returns, which makes presidential campaigns different. Going from no advertising to some advertising, an incompetent campaign message to a reasonably plausible one, or no get-out-the-vote operation to a decently organized one makes a really big difference in a candidate's fortunes. But the better a campaign already is, the smaller the effect of making it better.
Relative to campaigns for lower offices, presidential campaigns are always fairly well funded and competently run on both sides. Sure, some presidential campaigns are better run and have more resources than others. Yet even the worst modern campaign is better run, gets more publicity, and energizes its supporters much more than weak campaigns at lower levels.
The diminishing marginal returns to these tactics means the difference between the major parties' presidential campaigns has only a small effect on the outcome. Even relatively weak general election presidential campaigns get most of the benefits that they can from campaign tactics, leading the two campaigns' effects to mostly cancel each other out. What influences the outcome more are the things outside of the campaigns' immediate control, such as economic performance, the existence of an unpopular war, or the current president's approval rating.
Yet as you may have noticed, things are different this year. The Trump campaign is so weak that it appears to be affecting the race. Political science models predicting the 2016 election based on various fundamentals (i.e., variables that ignore the two candidates and their campaigns) mostly predict a very close election or a Republican victory. Trump is vastly underperforming these fundamentals. He is currently somewhere between 5 and 10 points behind in polling averages.
The reason is that his campaign is weaker than any in the modern media era. There is arguably a bigger mismatch relative to the opposing campaign than in any presidential election in American history. The many errors of messaging by Trump and his campaign staff are too numerous to list here.
The bottom line is that he has presented himself in ways that have little appeal beyond the Republican base, some of whom will vote for him because they like his message and others out of partisan loyalty. But many other Americans who would be willing to vote Republican this year are repelled by Trump.
The strange thing is that this means the details of Trump's campaign tactics matter a lot. Normally, both campaigns are competent enough that they are deep into the diminishing marginal returns for campaign communication. But this year, the Trump campaign has been so weak, I don't think diminishing returns have really kicked in yet. Trump could improve his fortunes a lot if he managed to run a weak but essentially normal presidential campaign.
Usually, political scientists scoff at most of pundits' analyses of campaign ads and speeches. Does this or that message resonate more with the electorate? It all seems more like theater criticism than serious political analysis. Don't pundits know that the only people paying close attention to these subtleties have already made up their minds?
That is usually true, but not this year. There seem to be a decent number of voters who at this point normally would have been convinced to vote Republican for president but are repelled by Trump. Many of these voters could be persuaded if only Trump could get them to perceive him as a conventional Republican.
I am skeptical that Trump and his campaign can pull this off. At various times, they have promised a pivot to a message more suited to the general election. But they revert after often only one day or one speech of acting like a conventional Republican. Trump seems incapable of acting different in public for very long, and with the hiring of Stephen Bannon from Breitbart as the campaign's new chief executive, his conduct is likely to get more extreme and outlandish. But just because Trump may not be willing to pivot doesn't mean it wouldn't work.
So as a political scientist, I have to constantly check my instincts when watching speeches and advertisements this year. My reflex is to say they don't matter much. That is still true for Clinton, who has run a fairly normal campaign, but not for Trump.
When we watch things like Trump's first television advertisement or his latest speech attempting to moderate his style (scripted and using a teleprompter!), the details are significant. There are people listening who want to vote Republican. All it takes is a competent campaign and a candidate who appears normal to bring them home.
The details of the message matter this time. If the Trump campaign could go from incompetent to just worse than average, it would have a shot at winning.