This I've never seen before in a political campaign.

The Harris campaign paid $1 million to Winfrey’s company on October 15, according to a report in the Washington Examiner, coming after a star-studded town hall that Winfrey hosted for the vice president in September.

Winfrey also appeared at Harris’ final rally in Philadelphia on the eve of Election Day, with the talk-show star offering a rare endorsement of a presidential candidate.

So Harris paid Oprah $1 million and got in return not just appearances -- but an endorsement.

Paying people doesn't break any laws generally, but it sure does sound a lot like prostitution, and is in your face and in the context of a campaign it would appear to me that it also violates the spirit if not the letter of campaign finance laws.  Paid political advertising must disclose who paid for it in all cases except.... it appears this sort.

Is that legal?  I'm not sure it is; did anyone at the time disclose that these were paid endorsements?

Of course not.

The FEC says that ALL public communication made by a political committee must be disclosed.  A paid appearance or endorsement is made by the committee and certainly would appear to fall under this law.

If the candidate or campaign authorizes and finances a covered communication (including any solicitation), the notice must state that the communication was paid for by the authorized committee. 

So paying an entertainer who endorses a candidate, and a "covered communication" is extremely broad in scope, must disclose conspicuously that it is in fact a paid solicitation and it has to be clear and conspicuous at the time.

This event, and its not just one (Oprah was not the only one paid) certainly appears to have been illegal as it looked like Oprah made that endorsement on her own initiative and at no time was it apparent that any of the acts, performances or other events in which celebrities showed up and endorsed Harris were paid to do so.

Will Harris be prosecuted for this?

She should be; we're talking about millions of expenditures on what amounted to paid advertising with zero disclosure under the "rubric" of "organic support."

That certainly appears to be illegal.