Bernie Sanders. (Photo by Matt McClain/ The Washington Post)

For the bajllionth time in this campaign, Bernie Sanders was asked over the weekend about the ongoing FBI investigation into  Hillary Clinton’s decision to exclusively use a private email server during her time as Secretary of State. And, for the bajillionth time, Sanders took a hard pass on the question.

Here’s the exchange with “Meet the Press” host Chuck Todd:

CHUCK TODD: Do you think Hillary Clinton needs a clean bill of health from the F.B.I. before she accepts the Democrat nomination?

BERNIE SANDERS: Well, I have said many, many times that I’m trying to run a campaign based on the needs of the American people. And that is raising the minimum wage to $15 an hour, paid family and medical leave, making public colleges and universities tuition-free. Those are the issues, by the way, that the American people are deeply concerned about.

CHUCK TODD: I understand that.

BERNIE SANDERS: But so I have not gotten into the email situation at all. There is a process unfolding. There’s an investigation that is going on. It will play out and we’ll see what happens.

That answer is, effectively, the same one that Sanders has been giving for the year-plus that he has been running against Clinton. And it’s also the reason why Sanders was never able to get over the top — or even come all that close — in the 2016 race.

Start with this premise: The only way Clinton loses a Democratic nomination fight to Sanders is if the race — ideally, for Sanders, in the early going — is deeply destabilized, to the point where people who felt like Clinton’s nomination was close to a foregone conclusion are forced to fundamentally re-evaluate that view.

Sanders tried that with hard pushes in Iowa’s caucuses and New Hampshire’s primary. Winning both of the first two races, he rightly surmised, would have forced people to re-think the idea of a Clinton coronation.

What Sanders should have done after he failed to pull off that double was begin to incorporate Clinton’s email troubles into his stump speech — using the ongoing investigation to raise questions in Democratic voters’s minds about both her trustworthiness and her electability.

But, time and again, Sanders turned away from that strategy — or anything like it.

It all began in an October debate in which Sanders famously/infamously told Clinton that “the American people are sick of hearing about your damn emails.”

I’m still not sure Sanders meant that line in the way it was received but the narrative was set.  Sanders didn’t view the email issue as pertinent to the election and wouldn’t use it as a cudgel against Clinton’s character.

He should have.

That’s not to say that if Sanders had aggressively raised questions about Clinton’s email practices he would have beaten her for the nomination. He still might not have.  But, rather than trying to seize on a primary in Pennsylvania or New York — both of which he lost — as the game-changing moment in the race, Sanders might actually have been able to prosecute a longer-term case against Clinton in a spot where she was (and is) clearly vulnerable.

Large majorities of the public — including the oft-touted independent voter — believe that the words “honest” and “trustworthy” don’t describe Clinton. The email story — even with Sanders virtually ignoring it — has helped erode those numbers over the past 14 months. The email controversy plays directly into many of the things that people — including Democrats! — don’t like or are wary of when it comes to the Clintons. The sense that the rules don’t apply to them. That they believe the world is out to get them. That they only keep people close who slavishly repeat back to them what they want to hear.

It was all there right for the taking. Any underdog candidate looking for a foothold into a race against a heavy favorite would seize on the email controversy in seconds.

Sanders is not, of course, “any underdog candidate.” He clearly believed the email issue beneath him and the sort of “big ideas” campaign he wanted to run.  He didn’t see politics as a game in which you do everything you can to exploit the weaknesses of the other candidate. And he acted on that sentiment.

That is, of course, why so many people rallied to Sanders in this race.  Promising a different kind of politics is appealing to large swaths of the public — most especially young people who flocked to Sanders in droves.

The problem with a practicing a different kind of politics is that the same old politics usually works. Sanders’s refusal to engage with Clinton over her emails was decidedly “on brand” (barf) for the unorthodox Vermont Senator. But, it also meant that he voluntarily jettisoned his single best weapon against her.

Sanders won the battle by ignoring Clinton’s emails. No matter what happens in California a week from today, he will have lost the broader war. And he only has himself to blame for it.