Because the expected-utility model fails to specify a strategy when voters are indifferent between alternatives, it can be extended easily to model voters who wish to base their strategies on factors other than their preferences for the alternatives. These voters may submit equal utility values for all candidates and have their votes based solely on their tie-breaking rules. This is consistent with our notion of rationality assuming that these other factors so outweigh any difference in a voter's preference between alternatives that the voter is essentially indifferent between them.
One situation where tie-breaking rules might prove useful involves voters who are indifferent between the candidates running in their party's primary but want to vote for whichever candidate is most likely to win in order boost the winner's share of the vote and make their party appear more unified. These voters might use a bandwagon strategy.
In theory, tie-breaking rules could be arbitrarily complex and involve many variables. For simplicity we limit tie-breaking rules to first-order functions of the predicted outcome and the maturity of the election.