It took just one question about Marco Rubio’s signature legislative achievement, the Senate’s Gang of Eight comprehensive immigration reform bill, to expose the tortured divisions inside the Republican field on the question of immigration. Rubio offered a talking-points answer that embraced a position — a path to citizenship — that is anathema to many Republicans, while at the same time sidestepping some key questions about his policy proposals. Then rival Ted Cruz rewrote his own history on the subject, followed by aides explaining that Cruz has now adopted a position — “attrition through enforcement” — that is likely to rekindle old fights in the GOP.

In the end, even an attentive and well-informed voter would have a hard time discerning whether either man was being entirely candid about his views.

The exchange began with this question, from CNN’s Dana Bash to Rubio: “You co-authored a bill with Democrats two years ago that allowed a path to citizenship for undocumented immigrants. Do you still support that path to citizenship, which means giving those immigrants rights, like the right to vote?”