There is an expression "voting-booth candidate", meaning someone that people don't feel comfortable telling the pollsters they'll vote for, even when they will.

There is an expression "voting-booth candidate", meaning someone that people don't feel comfortable telling the pollsters they'll vote for, even when they will. Jesse Helms polled as losing his senate seat a couple of times when he won. And Marion Barry's comeback bid as mayor of Washington, DC, looked dead: he won by a solid margin.