One of the more effective speeches during the Democratic convention came from former New York City mayor Michael Bloomberg.

In many ways, Bloomberg is what Donald Trump wants to be: a very rich guy who runs a media company and who converted that wealth into political power. Of all of the rich New Yorkers involved in the 2016 campaign, Bloomberg is the richest, worth some $40 billion, four times what Trump says he's worth and 13 times what Bloomberg (the media company) estimates Trump is actually worth. (Hillary Clinton, by contrast, is a lowly millionaire.)

Bloomberg is an ideological centrist in a way that now seems almost quaint, and his endorsement of Clinton on Wednesday night was more an anti-endorsement of Trump. He hammered Trump, questioning his actual wealth, calling him a con man and a hypocrite, and suggesting that Clinton deserved votes because she is "sane" and "mature."

And on Thursday, as Clinton was preparing to accept her party's nomination, Trump got mad about it.

Donald Trump says he wanted to hit some speakers at the Democratic convention and make their heads spin. (The Washington Post)

At an event in Iowa, he started talking about how he wanted to "hit" the Democratic speakers at the convention who were disparaging him. The choice of words was awkward, but it seems clear he meant it in the way he's used it throughout his campaign: To go after them with verbal or tweeted insults.

"I was going to hit one guy in particular, a very little guy," Trump said, making a clear reference to Bloomberg's stature. "I was going to hit this guy so hard his head would spin and he wouldn't know what the hell happened. He came out of nowhere!"

Trump continued to assail Bloomberg on Twitter on Friday morning, starting off with another joke about his height.

If Bloomberg were to run again, Trump wrote, he "wouldn't get 10% of the vote." Interestingly, a poll conducted in New York state in March showed Bloomberg beating Trump in a three-way contest with Bloomberg running as an independent. In New York City, Bloomberg got nearly twice as much support.

As BuzzFeed's Andrew Kaczynski pointed out on Twitter, Trump's attitude on Bloomberg's final term has changed pretty substantially of late. Here's Trump tweeting about Bloomberg during the latter's final term.

And shortly before he left office.

And, of course, praising Bloomberg for giving him a project.

The project in this case was a golf course in the Bronx, called Trump Golf Links at Ferry Point. Built on an old landfill, the course briefly had a problem with excessive methane output.

All of Trump's tweets above came before Bloomberg denounced him on television. As we've seen so many times in the past, nothing changes Trump's opinion on someone faster than their expressing a negative opinion of him.

Bloomberg has not yet been baited into tweeting a response, which no doubt comforted Clinton.

Update: ...but a former Bloomberg spokesman did.

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PHILADELPHIA, PA - JULY 27: President Barack Obama is joined on stage with Democratic Presidential Candidate Hillary Clinton during the third day of the Democratic National Convention in Philadelphia on Wednesday, July 27, 2016. (Melina Mara/The Washington Post)