The all-out war between Jeb Bush and Donald Trump is reaching bizarre new heights

Former Florida Gov. Jeb Bush (R) unveiled a series of broadsides against GOP presidential rival Donald Trump on Wednesday morning, including one labeled a "strikingly personal attack" by Time magazine.

It was only the latest in what has been an increasingly nasty back-and-forth between the two Republican heavyweights - an open feud that has bordered on the bizarre this week alone.

Bush's Wednesday salvo was released in the form of a quiz titled, "Which candidate are you?" His campaign said it was promoting the interactive ad on Facebook and "targeting people who like pages related to Donald Trump."

The quiz started with generic policy questions highlighting the real-estate magnate's past deviations from Republican Party orthodoxy.

For example, it asked people to say whether they would prefer a candidate who "supported the biggest tax increase in history" or "enacted $19 billion in tax cuts," the latter choice being a reference to Bush's record in office. Other questions hit Trump on gun rights, his past praise for Democratic presidential front-runner Hillary Clinton, and so on.

However, the quiz took a sharp turn on the final question, where it accused Trump of germaphobia and asked respondents if they would prefer a candidate without that pathological condition:

Trump has long been described in various press reports as a germophobe. He was once quoted calling handshakes "barbaric" and, according to New York magazine, he wrote in his 1997 book that he was a "clean hands freak" and detested shaking hands. 

"One of the curses of American society is the simple act of shaking hands, and the more successful and famous one becomes the worse this terrible custom seems to get. I happen to be a clean hands freak. I feel much better after I thoroughly wash my hands, which I do as much as possible," he reportedly wrote in "The Art of the Comeback."

Despite this backstory, Trump has been repeatedly photographed on the campaign trail shaking hands with supporters. Trump, who flirted with a 2012 presidential campaign, was also quoted in 2011 saying he would have no problem shaking hands if he ran for office.

"I will meet many, many people," Trump told the Des Moines Register then. "If I decide to run, I will be shaking hands with everybody."

Trump's campaign didn't respond to a request for comment from Business Insider on the germophobe attack, though if the past is any indication, the candidate is likely to blast Bush on Twitter later in the day.

Bush has repeatedly gone after Trump in recent days after spending weeks trying to mostly ignore Trump, who himself slams Bush in seemingly every campaign speech and media interview.

But with Trump's standing in the polls looking surprisingly durable, at least for now, the Bush broadsides are a clear signal that the Florida Republican is entering a new phase of his campaign.

"Jeb launched what we're calling Operation Backbone, finally lashing back at Trump's taunts," Politico's Mike Allen wrote in his Wednesday morning newsletter. "And Bush aides vow that the rabbit punches will continue - in person and online - in the two weeks between now and the Sept. 16 CNN debate at the Reagan Library."

A Bush aide further told Allen that the campaign's shots at Trump will "require repetition to break through the noise."

"[It was] increasingly clear Trump was trying to run a legitimate campaign and needed to be treated as any other candidate would. That includes exposing his record and agenda that will increase power in D.C. If nobody else is going to do it, we will," the aide said. "But it is a fight that is required and Jeb will take it on."

In addition to the Wednesday quiz, Bush released a new attack ad on Tuesday blasting Trump for his past support for Democrats and left-leaning policies. On Monday, Bush also zinged Trump for once praising House Minority Leader Nancy Pelosi (D-California) as "The Greatest":

Meanwhile, Trump has punched and counter-punched hard at Bush - including at least one arguably unusual attack of his own.

Trump published an Instagram video on Tuesday that grilled Bush for "honoring Hillary Clinton for her public service." The music choice for the video, an upbeat carnival tune, was atypical for an attack ad.

He also released a far more serious negative ad the day before. In another Instagram video, Trump spliced together images of alleged killers who crossed into the US illegally and comments made by Bush in 2014, when he suggested that many people cross the border illegally out of an "act of love" for their families.

That video reminded many political veterans of the infamous "Willie Horton" attack ad that former President George H. W. Bush used to tar Michael Dukakis as soft on crime during the 1988 presidential race. The ad has been widely criticized over the years for playing on racial stereotypes of criminals.

And in yet another social media clip last week, Trump touted the fact that Bush's mother, former First Lady Barbara Bush, once said her son shouldn't run for president. (She has since changed her mind.)

"Even Barbara Bush agrees with me," Trump quipped. 

Trump further ripped Jeb Bush on social media and said in a Wednesday interview on ABC that the former governor was only attacking him out of desperation.

"I think he had really no choice. He's doing very poorly in the polls. He's a very low-energy kind of guy. He really had to do something. So they're spending a lot of money on ads," Trump mused while accusing Bush of being in the pocket of his big donors. "He really had no choice."

Trump has previously taken credit for his rivals sinking in the polls after criticizing him, saying he was "greatly honored by that." He suggested to ABC that Bush's campaign was already tanking for that very reason.

"So far everybody who has attacked me has gone down. Let's see what happens here," he said. "You look at Jeb and you see what he's doing. And it's sort of an interesting thing - I think he had probably no choice. It's probably going to now stop because it seems to be backfiring on him, based on the polls. "