It’s one of the rules of smart politics: “If your opponent is shooting himself in the foot, get out of the way.” It’s hard to know who said it first, but right now it’s become a Bernie Sanders mantra. While Hillary Clinton struggles with her email difficulties and, more importantly, the vital perception of her honesty or lack thereof, Sanders wastes few opportunities to state that he has no intention of making the matter a campaign issue, which of course makes the matter a campaign issue.

This comes as the FBI continues to investigate whether former Secretary of State Clinton or her advisers mishandled classified material, which could be a criminal offense. The latest Friday-night dump from her private server suggests that there’s a possible top-secret “there, there,” leaving an embarrassing impression of incompetence on her part — or worse.

Once again, Sanders was ready with a passive-aggressive “I’m above it all” response: “There is a legal process in place which should proceed and not be politicized.” Translation: “If your opponent is shooting …”

Hillary’s biggest problem is the widespread belief that she’s not to be believed. For decades now, she, her husband and the people around her have been shooting themselves in the wherever by approaching controversy with obfuscation, parsing and dissembling that might impress their fellow lawyers but leaves us lesser intellects simply yearning for candor.

Oftentimes, it follows a familiar tactic to the one we’re now seeing with the email matter: deny, deny, deny, until the evidence contradicts. From her repeated “I did not handle or receive classified material,” we are now hearing from her that she did not initiate the transmission of classified material. In other words, it wasn’t her fault.

Another tactic is to grudgingly release incomplete information, and as more damning stuff comes out, to bank on the public being tired and worn down by the details. It’s become “old news” or, as she put it with this latest disclosure: “I’m really not concerned, because it’s the same story that has been going on for months now, and I just don’t think most people are as concerned about that as they are about what we’re going to do to get economy going and how we’re going to protect the Affordable Care Act …”

Those who liken her to Richard Nixon may be too brutal, but that same defense of dismissing the charges as trivialities was a familiar tactic during Watergate. There are two problems with that strategy: It didn’t work, and it doesn’t work. Reporters and investigators are not going to be deflected. More importantly, it looks dishonest. And this definitely is not a triviality. Mishandling classified material is a crime. We don’t know whether Hillary Clinton’s conduct was routine or innocent, nor how the feds are construing it. Of course, Republicans are not waiting to find out.

Meanwhile, more than a few Democrats have been dwelling on their worst-case scenario. What if she is indicted or what comes out reveals corruption that is truly damaging to her candidacy? Does this create an open path to the nomination for Sanders?

Many party pros shudder at that, in the same way that their GOP counterparts are horrified by the prospect of Donald Trump or Ted Cruz leading their ticket. In the Democrats’ case, those in the party establishment worry that Sanders — a self-described socialist — would get slaughtered by the Republican nominee, even one as outlandish as Trump or Cruz.

Would they turn to Joe Biden? Would he be drafted to ride to the rescue? Or maybe John Kerry, who is using his time these days to maintain a very high profile as secretary of state? He lost his bid for the presidency in 2004, but one can only imagine how easy it would be to persuade him to save the party and stay the enemies, mainly by hoping they’d shoot themselves every time they shot off their mouths. The smartest thing we can all do is duck for cover.

Bob Franken is a longtime broadcast journalist, including 20 years at CNN.