A spate of news articles on April 27 cover Rush Limbaugh’s recent boasts that he has influenced many Republicans to re-register as Democrats, in order to boost Hillary Clinton’s vote and thereby injure the Democratic Party. Here is an article from the San Francisco Chronicle. Although there is little evidence, the evidence that exists is significant. For example, an exit poll from Pennsylvania showed that 41% of the self-identified Republicans who had registered Democratic to vote in this month’s primary, and who had voted for Hillary Clinton, also said they would not be supportive of her in the general election.
This is a fertile field for political science and journalistic research, and it may influence court decisions when the constitutionality of open primaries is challenged by political parties.