Admittedly my legal-fu is weak

Inbox: The Trump campaign is suing Priorities USA https://t.co/QiBEZzSVs1

— Zeke Miller (@ZekeJMiller) June 24, 2020

But this lawsuit is by the Trump Campaign, not Trump, alleging a "false and defamatory statement" (slander, in other words) by PUSA, "a far-Left Super PAC," and Northland Television LLC which broadcast the ad in question, because "The purported statements of any authorized speaker alleged to have been made on behalf of the Trump Campaign impact the Trump Campaign."

No, don't worry about what the statement is right now; that's a question of fact, and first I'm interested in the law.

The damage of this allegedly false statement is that:

The Trump Campaign depends upon support from the public, and the Manufactured Statement in the PUSA ads tended to and tends to interfere with the Trump Campaign’s activities by prejudicing it in the public’s estimation.

And

The Trump Campaign’s effort to acquire votes necessarily rests on its and its candidate’s reputation.

Now, first, the petition opens with the acceptance, per NYT v. Sullivan, that:

“profound national commitment to the principle that debate on public issues should be uninhibited, robust, and wide- open, and that it may well include vehement, caustic, and sometimes unpleasantly sharp attacks on government and public officials.” New York Times v. Sullivan, 376 U.S. 254, 270 (1964). 

But this claim sounds like so much whinging, and the kind of thing a losing candidate's campaign engages in.  That, however, is still not the problem.  This, it seems to me, is the problem:

This case concerns a false and defamatory statement in a television advertisement produced and sponsored by PUSA, a far-left Super PAC, that has been distributed via social media and broadcast through various media outlets, including television stations such as defendant Northland Television, LLC d/b/a WJFW-NBC (“WJFW-NBC”), thereby causing material harm to the reputation of Donald J. Trump’s principal campaign committee, Donald J. Trump for President, Inc. (“the Trump Campaign”).  

It's my memory that slander and libel are, in the common law, "personal" actions.  That is, a person who has been slandered or libeled has the cause of action, and no one else (or no entity, either).  In fact, if the person claiming the slander/libel dies before or during the prosecution of the claim, the claim dies, too.  The estate, in other words, can't bring the action on behalf of the deceased.

So if PUSA did (big "IF") slander Trump, how can the Trump Campaign sue for damages?  If Trump had died, his estate couldn't bring the suit; how can the campaign do it?

Just seems awfully screwy to me.  As for the factual basis for the slander claim, I dunno; sounds pretty weak to me.

The claim is that PUSA's statement is "manufactured."  What the ad said was “The coronavirus, this is their new hoax."  Per Snopes, this is what Trump said:

One of my people came up to me and said, ‘Mr. President, they tried to beat you on Russia, Russia, Russia. That didn’t work out too well. They couldn’t do it. They tried the impeachment hoax. That was on a perfect conversation. They tried anything, they tried it over and over, they’ve been doing it since you got in. It’s all turning, they lost, it’s all turning. Think of it. Think of it. And this is their new hoax. But you know, we did something that’s been pretty amazing. We’re 15 people [cases of coronavirus infection] in this massive country. And because of the fact that we went early, we went early, we could have had a lot more than that.

It's from that speech that the PUSA ad was made.  Kind of unclear, honestly, what Trump's referring to, but it seems to be that coronavirus being a public health emergency is a hoax.  It's quite clear "this" refers to the coronavirus, not to anything else mentioned in that paragraph.  How different that is from the PUSA statement is rather hard to understand.  NBC News didn't see any difference at the time, either: 

President Donald Trump accused Democrats of “politicizing” the deadly coronavirus during a campaign rally here on Friday, claiming that the outbreak is “their new hoax” as he continued to downplay the risk in the U.S.

“Now the Democrats are politicizing the coronavirus,” Trump said. “They have no clue, they can't even count their votes in Iowa.”

FactCheck.org said the ad "twisted" Trump's comment, but that requires a pretty literal reading of both the ad and what Trump said; and their point is purely to fact-check ads based on a standard that doesn't always render defensible, or even intelligible, results.  Again, what else does "this" refer to in the sentence "And this is their new hoax"?  But "false and defamatory" and injurious to the Trump Campaign?

I don't see it.