I had almost posted this a couple days ago, but decided to hold on to it until I got to a couple of other pieces first. As it happens, thanks to kismet, news last night made that delay all the more timely. That's when Bernie Sanders gave a speech decrying Hillary Clinton for saying he was unqualified to be president, and then he went on to explain why she was unqualified.
There are a few problems with this. First, and most important, in the interview that Ms. Clinton gave on MSNBC's Morning Joe show, where she was asked if Bernie Sanders was qualified -- she never said he wasn't. Never said what Bernie Sanders angrily insists that she did. In fact, she ignores the question completely and pivots to address something else entirely. Indeed, the proof that she never once refers to Bernie Sanders as unqualified is that host Joe Scarborough has to ask her three times if she thinks Bernie Sanders is qualified, trying to get back to his question, and he finally moves on after she says that she will "leave it to voters to decide who can do a better job."
This isn't a matter of interpretation. You can see for yourself. She simply never says it. Here's the full interview. The question about being qualified (and its follow-ups) begin at the top, 30 seconds in --
And second, the reasons that Mr. Sanders gives in his speech to depict her as "unqualified" are merely issues he doesn't agree with her on (accepting legal funding from SuperPACS, accepting legal money from Wall Street, making certain votes in the Senate), all of which he feels very strongly about, but none of which are anything that have to do with qualifications.
Actually, there's a third problem here. It's that when you state pointedly that your opponent is "unqualified" -- something most candidates avoid in a primary race -- it becomes very difficult to backtrack on that afterwards and come together in support for party unity. That's why candidates might slam their opponents bluntly throughout over disagreements, but make sure the door remains open to subsequently support against the common "enemy" of the opposing party. Such words also allow that common "enemy" to quote you in the general election. (In this case, the Republicans would not be able to use the specifics of the Sanders charge because his reasons were all things they themselves agree with...) In the end, backtracking is possible, but such statements make it significantly more difficult.
All of which gets us back to the whole point of this here -- Paul Krugman's admonition here (written days before...) that Bernie Sanders keep running but tone down his angry rhetoric.
Timing is everything.