Forget about excusing this as "only a joke."  Jokes are a well recognized means of expressing hostility while pretending not to.  We have already seen a Bernie Bro attempt to assassinate a number of Congressional Republicans on a softball field, so any sane person understands that provocations issued by a person in a position of public trust and authority should not go anywhere near inciting violence.

Yet Alcee Hastings, a senior Democratic whip in the House of Representatives, and a prominent member of the Congressional Black Caucus, offered a threatening joke to a rally on Sunday.  As the poor quality of the video embedded below attests, TV cameras were not there to record the event, and Hastings probably didn't expect the broader public to become aware of his incitement.

Amber Athey of the Daily Caller:

Hastings was speaking at a rally in Sunshine, Fla. when he repeated a joke he heard from Ari Silver, the son of former Florida state legislator Barry Silver.  ("Collusion"? –T.L.)

"I will tell you one joke," Hastings said.  "Do you know the difference between a crisis and a catastrophe?"

"'A crisis is if Donald Trump falls into the Potomac River and can't swim,'" Hastings said, retelling the joke.  "'And a catastrophe is anybody saves his ass.'"

The crowd cheered and whooped in delight at the joke.

While specifically recommending against rescuing a dying Donald Trump, the joke makes the broader point that his death would be desirable.  This is in effect incitement.

Hastings, of course, does not belong in any position of prominence or trust, as he was impeached, convicted, and driven off the federal bench for soliciting a $150,000 bribe in return for leniency in the sentences of two mob-related felons.

A criminal inciting violence against a president is embraced by the voters of his racially gerrymandered district (Wikipedia: His "district includes most of the majority-black precincts in and around Fort Lauderdale and West Palm Beach"), the Congressional Black Caucus, and the Democratic Party.

Imagine any Republican having made the same joke about Barack Obama during his presidency.  It would have been the top story in the media until he was driven from office, with incessant pestering of other Republicans to denounce the offender and impeach him.