The one-time favourite for the Republican presidential nomination, Jeb Bush, turned in a stinker in the third Republican debate, critics say.

The reviews have been scathing, from New York, to Los Angeles, to Wall Street.

His donors were already nervous after the Bush campaign made massive cutbacks to staff and salaries last week.

• Republicans target ‘insult monger’ Trump
• ‘Jackass’ Trump the most popular Republican
• The most outrageous quotes from the Republican debate

But Mr Bush did not step up, and even afterwards he could only offer this uninspiring defence of his performance.

“I’m not a performer. If they’re looking for entertainer-in-chief, I’m probably not the guy,” he said.

Critics said Mr Bush began to lose ground when he made a ham-fisted attempt to attack Marco Rubio’s patchy voting record in the Senate, comparing it to a “French work week”.

Senator Rubio hit back, arguing that Governor Bush was only attacking him because they are “running for the same position” and “someone has convinced” him to.

Mr Bush badly needed to lift for this debate after a series of fairly pedestrian performances.

It matters because, for all his family’s political connections and the massive amounts of money he has raised, Mr Bush has simply not delivered on the stump.

Jeb Bush ‘totally out of his league’

Peter Beinart, a contributing editor to the Atlantic magazine, said Mr Bush has turned out to be a “terrible candidate”.

“He was totally out of his league against Marco Rubio, as he’d been out of his league against Donald Trump before,” he said.

“When the money starts drying up and establishment Republicans who are worried about finding someone who can take on Trump or [Ben] Carson realise that Rubio is the only person who can do that, I think this could end fast.”

The morning after the debate, Mr Bush was back out on the campaign trail.

“It’s not about the big personalities on the stage, it’s not about performance,” he said.

“It’s about leadership and the leader today in this country needs to be unifier.”

Mr Bush still has resources that other candidates do not have that could enable him to stick out the campaign if current poll leaders Trump and Carson, drop out.

Establishment Republicans, who are horrified by the thought of either Trump or Mr Carson taking the nomination, are waiting for that to happen.

But they may not be prepared to wait for Mr Bush to get his act together in time.

Instead, his former friend and protégé Senator Rubio just made a very strong pitch to carry the Republican establishment’s flag into 2016.

– ABC