Because the larger bloc is larger, a small gain in its margin or turnout is worth more votes than a large swing inside a smaller one, so a party is claimed to gain more by working its own base than by courting others.
The claim is arithmetic before it is political. Where one bloc is four times the size of another, a one-point gain in the larger is worth a four-point gain in the smaller, so the return on persuasion depends on the size of the group as much as on how persuadable it is. Sailer set it out in 2000. The case usually cited for it is 2016: Trump's margin among white voters without a degree moved about six points from 2012, and in Michigan, Wisconsin and Pennsylvania that shift was worth more than anything else on the board. Two features of that election do not match the prescription. White turnout was flat rather than surging, and Trump's share among Black and Hispanic voters rose by two or three points rather than being written off, so 2016 bears out the arithmetic more cleanly than the strategy built on it.
In practice
- A one-point gain in a group holding seventy per cent of the vote outweighs a ten-point gain in a group holding five per cent, and no amount of enthusiasm about the second changes the multiplication.
- Its general form is the base-versus-persuasion trade-off, which political science treats as an open empirical question rather than a settled strategy for any party.
- Possible explanations
- The explanation is arithmetic: where one bloc is much larger, a small proportional gain in it yields more votes than a large gain in a smaller one, so the return on persuasion depends on the size of the group being persuaded.
- In its favour
- The arithmetic is not in dispute, and campaigns do allocate resources by expected votes per pound, which is the same calculation.
- Against it
- Whether the gains it recommends are available without losing votes elsewhere is the disputed part, since positioning to win margin in one bloc can cost support in others, and it is an electoral hypothesis rather than a tested finding.
- Standing
- An electoral hypothesis rather than an established finding. The arithmetic is not in dispute; what is disputed is whether the gains it points to are as reachable as the model assumes, whether writing off other blocs costs more across several cycles than it returns in one, and how fast the bloc sizes it depends on are moving. The 2016 case fits the arithmetic and departs from the prescription on turnout and on minority vote share.
- Subject
- Law & Politics
- Essay
- Competing accounts of how power works