Jeb Bush begins challenging Donald Trump head on

Republican presidential candidate Jeb Bush has escalated his feud with Donald Trump, betting that he can re-energise his stalled campaign by challenging the billionaire businessman head on.

It’s a risky strategy for the former Florida governor, still considered the GOP frontrunner by many party officials, but a move his advisers suggest is necessary to reverse Trump’s unlikely ascension to the top of the 2016 presidential class.

Bush intensified his criticism of the ex-reality TV star on multiple fronts, first releasing a video featuring clips of Trump himself promoting traditionally liberal positions in old interviews.

“You’d be shocked if I said that in many cases I probably identify more as a Democrat”, Trump says in the video produced and promoted by the Bush campaign titled “Liberal Things That Trump Says.”

In a subsequent Fox News interview, Bush charged that “Trump is more a Democrat than a Republican”.

Speaking to reporters in English and Spanish in Miami later in the day, Bush said: “He attacks me every day. He personalises everything.

"If you’re not totally in agreement with him, you’re an idiot, you’re stupid, you have low energy, blah, blah, blah. That’s what he does.”

The Bush campaign reports that the political assault was not an isolated incident, but part of a broader strategy to engage Trump more directly.

While the two have traded jabs before, the approach marks a shift for Bush, who previously preferred to ignore Trump’s bombast.

“Trump has attacked Jeb’s wife, his mother, he’s taken him out of context and lied about his record,” said Bush spokesman Tim Miller.

“It’s incumbent upon us to not just set the record straight about Jeb’s record, and not just fight back, but also expose Trump as somebody who’s completely misrepresenting himself to voters,” he said.

Miller promised the campaign would release “more digital products”, such as the video, in the coming days, while Bush would continue to be aggressive on the campaign trail.

Bush, the son of one president and brother of another, is certainly not the first Republican presidential contender to go after Trump, yet he has the highest profile of the critics.

The struggles of Trump’s other critics offer a pointed reminder of the risks of confronting a man whose business is confrontation.

“Fighting with Donald Trump is like wrestling in the WWE,” said Republican pollster Frank Luntz, himself the target of insults from Trump.

“It doesn’t get you anywhere, and you know it’s going to hurt.”

Trump released a video of his own later in the day highlighting Bush’s praise for the Clinton family.

Trump noted on Twitter that other presidential contenders have tried to take him on.