Not since Marco Rubio mocked Trump’s supposedly small hands — a stand-in, the unspoken logic went, for lacking in another anatomical department — has one of his rivals tried to play the personal insult game against the disparager-in-chief. The common belief is that it’s a lost cause and only backfires, as Rubio learned the hard way, on the person who tries.

Trump fired first on Sunday. In a series of tweets, he blasted Bloomberg’s eponymous news service as “fake,” accused him without evidence of receiving special treatment from the Democratic National Committee as part of a conspiracy against Bernie Sanders, and mocked the billionaire former New York mayor’s diminutive stature.

Mini Mike is part of the Fake News. They are all working together. In fact, Bloomberg isn’t covering himself (too boring to do), or other Dems. Only Trump. That sounds fair! It’s all the Fake News Media, and that’s why nobody believes in them any more. — Donald J. Trump (@realDonaldTrump) February 2, 2020

And in his pre-taped Super Bowl interview with Fox host Sean Hannity, Trump referred to Bloomberg simply as “little,” rather than his actual name. He also claimed Bloomberg is asking to stand on a box at future debates, which Bloomberg's campaign denied.

“Why should he be entitled to that? Really! Does that mean everyone else gets a box?” Trump said. “It’s very interesting.”

Bloomberg, who is listed as 5 feet 8 inches, responded in brief remarks to reporters in Los Angeles.

“I stand twice as tall as he does on the stage that matters,” Bloomberg said. “This is what happens when somebody like me rises in the polls. All of a sudden the other candidates get scared and I think Donald Trump knows that I can beat him. And that’s why he comes back with those kinds of comments.”

Bloomberg adviser Tim O'Brien lobbed another insult at Trump on MSNBC. "What I’ve said to people is when you get inside Donald Trump’s head, all you’re going to discover that you find there is a putter, a cheeseburger, a porn video, and somebody else’s credit card," O'Brien cracked.

Bloomberg, more than any other Democrat, has focused exclusively on Trump and relishes the opportunity to get under the president’s skin. His speeches are loaded with mild insults, often variations on jokes about how Trump is a phony billionaire who merely played a CEO on reality TV.

He’s slammed Trump over his reported comments that undermine the military and in an ad released Friday on “Fox and Friends” featured unflattering pictures of Trump golfing while Bloomberg ribs that the only job Trump is qualified for is running a golf course.

Bloomberg has grown his support in some national polls to the double digits. In recent weeks, he’s drawn several crowds of 500 or more attendees, including more than 1,000 at events Saturday in Phoenix and Denver.

But it’s Bloomberg’s $300 million-and-growing ad campaign — and the hundreds of millions more he’s pledged to spend to take out the president — that Trump has obsessed over.

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Trump on Sunday also trashed Bloomberg’s ubiquitous TV ads, calling his late gambit backed by hundreds of millions of his own dollars a waste of money. Trump wrote in one of the tweets, “He is going nowhere, just wasting his money.”

Trump’s tirade came after the DNC informed campaigns Friday that it was eliminating a requirement that candidates raise money from a minimum number of donors to become eligible for its upcoming debate in Nevada, paving the way for Bloomberg to make the stage. Bloomberg remains three polls short of qualifying, but he does no fundraising and needed a rule change in order to have the chance to participate in upcoming debates.

POLITICO reported last week that Bloomberg and some of his opponents were in talks with the DNC to rewrite their rules — Bloomberg for the attention that a debate brings and his Democratic rivals because they want him to face more scrutiny.

During the Super Bowl, Bloomberg will air a 60-second ad focused on gun control and his record, while Trump is running two 30-second spots.