This is obviously unprecedented in modern presidential elections. Typically, the candidates have similar resources and campaign organizations. Typically, it is difficult for one candidate to have a large advantage in televised advertising or fieldwork. In 2012, for example, my research with Lynn Vavreck showed that neither Barack Obama nor Mitt Romney could sustain a durable advantage in advertising. Obama’s edge in fieldwork did appear to net him votes, although not enough to be decisive in the electoral college.

By comparison, Trump is being vastly outspent in advertising and is limited essentially to whatever field organization the Republican National Committee can provide — which will be exceeded by Hillary Clinton’s, much as Romney’s was exceeded by Obama’s. How much will this cost him on Election Day?

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Probably the best estimate comes from a recently published piece by political scientists Ryan Enos and Anthony Fowler. They show that the effect of the 2012 presidential campaign on voter turnout was quite large, about 7-8 points overall.

They arrive at this estimate by analyzing a sort of experiment: media markets that span state boundaries, such that part of the market falls in a battleground state and part doesn’t. Voters in one of those markets would be potentially exposed to the same amount of televised political advertising but different amounts of other campaign activity. In particular, you would expect that the battleground state voters would be far more likely to be contacted by campaign fieldworkers, who generally aren’t going to contact voters outside of battleground states.

Enos and Fowler found that voter turnout within these markets was much higher in the battleground state portion than the non-battleground state portion. About 7-8 points higher, in fact. Most of this, they argue, can be attributed to canvassing by the campaigns via door knocking and phone calls, which other political science research has shown to be particularly effective. The increases in turnout were even larger — closer to 10 points — among the strongest partisans, who should be particularly susceptible to mobilization attempts.

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Notably, Enos and Fowler also found that these increases in turnout were similar among Democrats and Republicans. As they noted in a previous Monkey Cage post, this implies that both the Romney and Obama campaigns were able to mobilize voters successfully.

So what is the implication for Trump if he doesn’t have a full-fledged field organization? Fowler suggested thinking through the math like this.

Imagine you have a place where 50 percent of the voters support Trump and 50 percent support Clinton. If equal proportions of Trump and Clinton supporters vote, the candidates would obviously tie with 50 percent of the vote each.

Now suppose, for example, that 55 percent of Trump supporters vote but 62 percent of Clinton supporters vote — that 7-point effect again. Now Trump’s share of the vote is 47 percent. The math is: (.55*.50)/[(.55*.50)+(.62*.50)]. In other words, Trump’s disadvantage in campaigning turned a tie into a 6-point defeat.

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Of course, there is always uncertainty in extrapolating from a previous election. And perhaps the RNC and Trump will ultimately construct some semblance of Clinton’s field organization, thereby narrowing Trump’s disadvantage.

But clearly the Trump campaign faces a major challenge at this point in time. When you’re down 7 points in the polls and early voting is already starting, you need every vote you can get. But the Trump campaign seems more likely to leave votes on the table.