So on the Sunday talk shows Bernie Sanders said he's going to challenge Clinton at the DNC. He keeps changing the story. I don't think it's because he has changed as some people think, rather he's seen his own contribution numbers, numbers we can't see, and they tell a story. The story is that (just guessing) his backers think he's given up so they aren't contributing. So if he wants money to keep flowing he has to sound like he's fighting, even if he isn't.

What story must his numbers tell? Well, we know that they're down dramatically in April. It's likely that they are down week to week within April, though we don't see those numbers. In other words he probably raised more in the first week than he did in the last week. Which probably says that May is going to be even worse unless he does something to stimulate the giving. 

Why should he care if they contributors keep giving, you might ask. I ask that too. I can only guess, and I'd rather not do that. But it seems that if the campaign is winding down, he doesn't need more money.