Image copyright Reuters Image caption Jeb Bush is bidding to become the third member of his family to become president

One of my more memorable moments on the campaign trail so far came after the Republican debate in Boulder, Colorado, when I found myself chasing Jeb Bush down a corridor, attempting to lasso him with a boom mike - a contraption which looks like a fishing rod, with a rodent-like furry microphone attached to the end.

Bush was smarting from a lamentable debate performance, during which his attempt to ambush his one-time protege Marco Rubio with an attack on the Senator's absenteeism from Capitol Hill had boomeranged horribly.

The headline "Boulder Crushes Bush," was already doing the rounds on Twitter. In the spin room, veteran journalists composed one-word obituaries: "Finished."

Suffice to say, Bush was not in the mood for a lengthy post mortem with the BBC, and headed down the corridor with an uncharacteristic burst of energy.

Yet when I asked him if his performance was up to scratch, that furry microphone positioned temptingly just below his jawline, he was sufficiently riled up to answer.

"It's not a performance," he harrumphed, "I'm running for President of the United States."

Media playback is unsupported on your device Media caption What could Jeb learn about campaigning from his older brother?

Many of Bush's problems were summed up in those four words: "It's not a performance."

In a conservative movement that continues to deify its movie-star president Ronald Reagan and which lauds Donald Trump, who is better known these days as a reality TV star than a property developer, "performance" has never been more important.

The debates are generating record-breaking viewing figures. Politics has become a branch of the entertainment industry, with television rather than social media the dominant platform.

So candidates who dismiss the theatrical requirements of modern-day campaigning do so at their peril.

Brash performers

Judging by the enduring popularity of the boastful billionaire, the Republican base likes brash performers, the type who would not look out of place hosting WWE professional wrestling.

Alas, Jeb Bush looks like he would be more at home presenting the graveyard shift on National Public Radio.

Image copyright Getty Images Image caption Anti-establishment candidates such as Ben Carson and Donald Trump are seemingly in vogue

Bush's frustration that night in Boulder was not just palpable but also understandable.

With eight years' experience as Governor of Florida, with binders full of policy proposals at his fingertips and with a detailed knowledge of foreign affairs, he has the smarts to be president.

What's lacking is a winning personality and the requisite flair for political vaudeville.

Bush's great misfortune is not just that he is an establishment candidate running at a time when anti-establishment candidates are in vogue.

He also suffers from the fact that experience and expertise seem less important than sheer entertainment value.

During last week's debate in Milwaukee, presumably frustrated by the policy incoherence of Trump and Carson, his anger again came to the boil.

"We have to win the Presidency," he complained. "And the way you win the Presidency is to have practical plans."

He's right, of course. What's more, policy wonks and contemplative thinkers can reach the White House.

However, as Bill Clinton (wonk) and Barack Obama (brooding thinker) both demonstrated, they need also to have a feel for political stagecraft.

Presumption of victory

The early frontrunner, for some the presumed nominee, Bush was at his strongest when voters had not yet attached a personality to his famous name.

And that is hugely ironic, because most commentators thought his name, and the history and sense of entitlement that went with it, would prove to be his biggest handicap.

As it turns out, the problem is not Bush but Jeb - or Jeb!, as his campaign banners have rebranded him, in the hope of vesting him with much-needed lustre.

Image copyright AP Image caption Marco Rubio has stolen a march on his former mentor

From bungling the most obvious question that he was likely to be asked - did he support his brother's decision to invade Iraq? - to launching that ill-conceived attack on Rubio, Jeb has not looked ready for primetime.

Again, this is ironic, given that the presidency has been the target of his ambitions for so long.

Some candidates grow in stature as the campaign goes on, as Marco Rubio has demonstrated.

Others suffer stage fright, or simply prove temperamentally unsuited to prosper in a modern-day campaign.

Here, Bush runs the risk of joining the roll call of candidates who had strong paper qualifications to be president but not the skills as a campaigner to win the presidential nomination - a list that includes George Romney (the father of Mitt), and Rudy Giuliani.

Political problem

Bush not only faces a personality problem but a political one.

He himself acknowledged this at the start of his campaign when he said, rather nobly, that he was willing "to lose the primary to win the general."

Image copyright AP Image caption Rudy Giuliani was thought to be good presidential material

By this he meant that he would take moderate positions on issues like immigration that risked alienating the insurgent right but which would make the Grand Old Party (GOP) more inclusive.

At the moment, however, he is struggling even to win over pragmatists in his party.

Here is it worth considering Jeb's political bloodline, because the story of the Bushes in some ways doubles as the story of the modern GOP.

The dynastic patriarch Prescott Bush, a Republican Senator from Connecticut, was the kind of northern-eastern patrician who used to dominate the party.

George Herbert Walker, his preppy son, moved from New England to Texas, not only to make his fortune as an oil man but because the Republican party's political centre of gravity shifted after the civil rights era from Wall Street to the Sunbelt and the South.

His eldest son, George W Bush, a born-again Christian, benefited from the marrying of the conservative movement with the evangelical movement.

Jeb Bush hoped he could write a new chapter not just in family lore but also in GOP history.

A fluent Spanish-speaker, married to a Mexican-American, he looked like the ideal figurehead for a party desperate to make inroads into Latino communities.

Unfortunately for him, the Republican base seemingly has decided on a wholly different path.

Trump, who has electrified the base not just with his showmanship but his hard-line stance on immigration, has framed the contest and given it a heavily anti-immigration tone.

The Bush obituaries drafted in Boulder are precipitate.

Though his campaign has been forced to make cutbacks, he has enough money to remain in the race.

Jeb Bush:

Born 11 February 1953 in Midland, Texas. Son of President George Bush, and younger brother of President George W Bush.

Married Mexican Columba Garnica Gallo in 1973. The couple have three children.

Moved to Miami, Florida, in 1980, where he helped form what would become a successful real estate company, the Codina Group.

Entered politics in 1984, as chairman of the Dade County Republican Party.

In 1994, ran for governor against a popular incumbent, Lawton Chiles, losing by a small margin.

Became governor in 1998, after campaigning on issues normally regarded as Democratic Party territory: public school education, urban renewal, and Medicaid funding.

During his eight years as governor, he overhauled the state's education system and pushed for substantial tax cuts.

Profile: Jeb Bush

Besides, he has always set out to play a long game, hence his statement about losing a few battles in order to ultimately win the war.

As primaries are held in the so-called Blue Zone, the populous Democrat-leaning states where GOP primary voters tend to be more moderate, Bush's pragmatist message should resonate more strongly.

This Blue Zone, as the veteran pundit Charlie Cook and others have pointed out, explains why establishment candidates so often end up on top.

That said, after Boulder, he has been usurped by Marco Rubio.

Image copyright Getty Images Image caption Senator Edward Kennedy lost the 1980 Democratic nomination to Jimmy Carter

Looking ahead to primary season proper, one could imagine an outpouring of sympathy towards Bush should, God forbid, something happen to his father.

That said, there is not much love for George Herbert Walker Bush on the Republican right, where he was always suspected of being a blue-blood moderate rather than a red meat conservative.

Or, put another way, a New Englander rather than a true Texan, who betrayed conservative principles by breaking his famous "read my lips, no new taxes" pledge.

The epic irony is that Jeb Bush was long seen as the great political talent in his family.

Presumably, it will be of little comfort that the Kennedys once said the same thing of young Teddy.