Bernie Sanders must be livid at Hillary Clinton.

It’s a belatedly developed case of rage over her disparagement of his followers as basement-dwelling losers.

Sunday, Sanders was making excuses for Clinton — he got her point, it wasn’t like it sounded. Yesterday, he suddenly developed a scheduling conflict, and bailed on an event where he was supposed to be helping her win over those disgruntled millennials, who love him and are at best underwhelmed by her.

A scheduling conflict? At this critical point in a hotly contested campaign, when the unpopular Democratic nominee is going to need every one of those Bernie backers she can’t help but look down her nose at?

As a bleeding-heart liberal, what could be more important to Bernie than seeing Hillary in the Oval Office? Maybe his dignity?

Here’s what he’s being asked to swallow:

“Some are new to politics completely. They’re children of the Great Recession. And they are living in their parents’ basement,” Clinton told her supporters at a February fundraiser, in a leaked tape. “They feel they got their education and the jobs that are available to them are not at all what they envisioned for themselves. And they don’t see much of a future.”

Clinton, not much liked even by a lot of people who already intend to vote for her, needs those basement voters, and she needs Bernie on the stump actively convincing them now more than ever that she’s their best option.

Democrats have been doing everything they can to make this week all about Donald Trump’s tax returns and the Trump Foundation. What they apparently have forgotten is, they need to shore up their own ranks. Instead, the campaign canceled events where Clinton and Sanders were supposed to share the stage in Iowa yesterday. As it stands, Sanders is supposed to appear without Clinton tomorrow in Iowa and Wisconsin.

Pretty thin gruel, rallies to stir up the troops for someone who has not only insulted them, but doesn’t want to face them.

Hillary Clinton should have taken Jeb Bush’s line more seriously when he told Donald Trump, “You can’t insult your way to the White House.”

But it wouldn’t hurt Trump — under attack for being wealthy — to remind voters that Hillary’s daughter isn’t living in her basement. She has a $10 million apartment in New York.