Ever since Donald Trump has risen to the top of the polls, Republican strategists have questioned whether those polls might be overestimating his support.

There is evidence to support that theory.

We wrote about Mr. Trump’s support on Sunday, using polling data provided by Civis Analytics, a Democratic data firm founded by the 2012 Obama campaign’s analytics director, Dan Wagner. It showed Mr. Trump faring worse than in many recent public polls, but it was not enough to call his lead into question.

An analysis of the data revealed that he fares best among voters who don’t regularly participate in primary elections. Nevertheless, he still leads the other G.O.P. candidates, even among the most frequent voters.

The analysis also suggests that although Mr. Trump fares better among irregular voters, it’s not by an unusual amount. And some other candidates also do better with infrequent voters.