There was a point where Jeb Bush's success seemed inevitable.

He declared his candidacy for the Republican presidential nomination early. He raised huge sums of money.

He lined up high profile endorsements and backers. It looked as if he would scare off any potential challenges, making his success look unstoppable.

And looking at the polls, it seemed to work. All the predictions were the US would once again face a Clinton-Bush battle for the nation's top job.

But now, Bush goes into the third Republican candidate debate on Boulder, Colorado, on Wednesday fighting for his political survival.

He needs a breakout moment. Something that grabs the attention of the American public.

And if he fails to deliver, many of those big backers and prominent supporters might think it's time to shop around for another candidate to endorse.

Independents targeted

Bush wanted this campaign to be different. He told business leaders before he launched his campaign he was "willing to lose the primary to win the general".

He knew not all of his positions chimed with the Republican base; he took a step away from the party's orthodoxy on education and immigration.

But he believed that would play better with independents and wandering Democrats if he got through the primary process.

He knew taking hard core positions to appeal to the base might get you the nomination, in the way Mitt Romney did, but that wouldn't guarantee you the White House.

And he knew Republicans really want to win the White House.

After eight years as governor of Florida, he was seen as someone who enjoyed drilling down on policy. Perhaps he wasn't dynamic, but he would get the job done.

But then like everyone else in the Republican race, he was blown off course by Donald Trump.

Trump phenomenon

The property and business mogul stole a lot of oxygen from other campaigns, dominated the headlines and the media coverage, and suddenly found himself leading the polls.

Like others, Bush thought it was a summer thing.

His campaign was sure the Trump phenomenon would play itself out.

People would get bored. The candidate would struggle to answer serious questions. His gaffes and sometimes outrageous statements would be punished by the voters. But that didn't happen.

Bush continued to campaign, to shake hands and hold rallies. But his support seemed to go down rather than up.

Backers got nervous and forced the campaign to cut back on staff and reorganise.

Senior figures, including his dad and his brother, both former presidents remember, huddled together for two days this week to see what needed to be done to fix it.

'Cool things'

Bush hasn't helped himself.

When asked his reaction to a school shooting in Oregon, he said "stuff happens." That irritated many and seemed like pandering, a failure to confront gun violence rather than upset core supporters.

And then at the weekend, there was a petulant outburst when he told a crowd in South Carolina: "If this election is about how we're going to fight to get nothing done, then I don't want to be any part of it.

"I've got a lot of really cool things that I could do other than sit around, being miserable, listening to people demonise me, and me feeling compelled to demonise then. Elect Trump if you want to do that."

But Bush knows when he steps on the stage in Boulder, he will have to show some fight.

He'll have to respond to any barbs from Trump with interest and insert himself back into the race.

He has to have not just a good night, but a really good night.

Otherwise, his backers will leave and his campaign will become the biggest yet to fold.

And Bush will be given plenty of time to do all the "cool things" he wants.

Source: Al Jazeera