A day after Hillary Clinton fell ill at a 9/11 memorial service, prompting her campaign to acknowledge a previously undisclosed pneumonia diagnosis, the far-fetched idea that Democratic officials could move to replace her as the party's presidential nominee is floating around in all the predictable places — and at least one not-so-predictable place.

Breitbart, Newsmax, Infowars, Lifezette and Gateway Pundit are among the conservative news sites suggesting Clinton could be pressured to leave the race because of health concerns. British tabloids are all over the idea, too. The Drudge Report blared Monday morning that Clinton running mate Tim Kaine is "in the bullpen," like a relief pitcher getting ready to take the ball from a starter who can't go the distance.

None of this is surprising — or likely. Many stories are based on tweets by David Shuster, a former MSNBC anchor. Breitbart referred to Shuster as a "left-wing reporter," as if to say, "You should believe that Clinton might be forced out because even a liberal says so."

Shuster, of course, doesn't actually have a reputation as a Clinton sympathizer. You may recall that back in 2008, while at MSNBC, he said on the air during the Democratic primary that Chelsea Clinton was "sort of being pimped out in some weird sort of way" to lobby superdelegates on behalf of her mother.

Hillary Clinton called the remark "incredibly offensive" and said she expected MSNBC to take "appropriate action" against Shuster. (The cable channel suspended him for two weeks.)

So Shuster is perhaps not as shocking a source as Breitbart would have you believe.

But what truly was unexpected was to hear talk of replacing Clinton on NPR coming from commentator Cokie Roberts, who has taken a strong stand against Donald Trump. On "Morning Edition" Monday, Roberts seemed to catch host David Greene off guard as they discussed the former secretary of state's early exit from Sunday's ceremony in New York.

ROBERTS: It gives Trump ammunition. And he's been setting her up for this for months. I mean, back in January he started saying that she didn't have the strength and stamina to be president. And he knew at some point in the campaign schedule that she, like all candidates, would get exhausted. But the fact that it comes now, when the polls are tightening and Democrats were already saying that Hillary was the only candidate who could not beat Trump, and it's taking her off the campaign trail, canceling her trip to California today, it has them very nervously beginning to whisper about having her step aside and finding another candidate.

GREENE: That is no small thing to say. Is that a real thing? Or is this just some nerves after a weekend of —

ROBERTS: No, I think it's unlikely to be a real thing. I'm sure it's an overreaction of an already skittish party. But, you know, they have looked at what happens in that circumstance. The Democratic National Committee chair convenes the committee, and they vote. Now ironically the candidate that everybody looks at is Joe Biden, who of course is older than Hillary Clinton, but then again so is Donald Trump, and we know nothing about his health.

GREENE: But I guess important to say, though, there is no indication — I mean, the Clinton campaign has said that she is fine and, I mean, is going to resume her schedule.

ROBERTS: Absolutely, and that is happening, we assume. But there is enough unhappiness that this kind of sotto voce stuff is going on.

Roberts's report of Democrats "beginning to whisper" came with qualifiers ("overreaction," "unlikely to be a real thing"). And it is worth remembering that nothing has come of periodic reports about Republican Party officials plotting to ditch Trump whenever he says something particularly provocative. These dramatic scenarios are fun for some analysts to talk about, but just about impossible to imagine.

Still, Roberts has brought the idea into the mainstream media. It will be interesting if anyone else outside the partisan media orbit ventures anywhere near it.