M. Battaglini, V. Leone Sciabolazza, Lin M., E. Patacchini, Money, Influence (and Death) in U.S. Politics.

It has long been observed that there is little money in U.S. politics, at
least compared to the stakes. This has led researchers to question whether
contributions are instrumental political investments since, in this case, we
would see more of them. But what if contributions are not fully observable
or non-monetary in nature? Can large donors gain sway over candidates
even with small contributions? We address this question with a new data
set on the top 1000 donors in U.S. congressional races. We do not focus
on what they give (which indeed may be unobservable), but on what they
accomplish. Since top donors do not randomly support candidates, we
base our identification strategy on information about top donors’ deaths
and the observed variations in candidates’ performance after these events.
We document that, on average, the death of a top donor decreases a
candidate’s likelihood of being elected by 3%. Candidates’ outcomes are
not simply affected by the decrease in their monetary contributions, but
also by the prominence of the deceased donor: Candidates losing the most
influential top donors (as measured by Google searches of their names and
other measures) are those who suffer the most.