If you’re a single-issue voter and your single issue happens to be “knows how to get into the New York City subway system,” you may be out of luck with the current Democratic field.

Cameras rolled Thursday as Democratic frontrunner Hillary Clinton attempted — five times — to swipe onto the platform of a Bronx-bound 4 train.

Clinton told reporters it had been “a year, year and a half” since she last rode the subway. “I think it was during my first term [as Senator] when we changed from token to MetroCards.”

“I’m proud to be a New Yorker,” she added. “We don’t use a token on the subway.”

Her remark was a dig at rival Bernie Sanders, who just last week shocked the greater metropolitan area by admitting he still thought passengers entered the subway with tokens. During a rough meeting at The New York Daily News last week, Bernie and the editorial board had this awkward exchange:

Daily News: When was the last time you rode the subway? Are you gonna a campaign in the subway?

Sanders: Actually we rode the subway, Mike, when we were here? About a year ago? But I know how to ride the subways. I’ve been on them once or twice.

Daily News: Do you really? Do you really? How do you ride the subway today?

Sanders: What do you mean, “How do you ride the subway?”

Daily News: How do you get on the subway today?

Sanders: You get a token and you get in.

Daily News: Wrong.

Sanders: You jump over the turnstile.

Daily News: We would like our photographer to be there when you jump over the turnstile.

The subway isn’t the only platform Clinton and Sanders have sparred over this week. In preparation for an intense fight for New York primary votes, both candidates have tested new attack lines, including yesterday when Sanders suggested the former Secretary of State may not be “qualified” to be president. Clinton and Sanders will duke it out at a debate in Brooklyn on April 14; New York’s primary is on April 19.

Photo: Flickr user Steven Pisano.