Not for the first time, an American who wants to be President of the United States will have to defeat a big, vociferous section of his own party before he gets to do battle with his official opponent.

Yet for Jeb Bush, facing down mistrustful conservative Republicans to win the nomination for 2016 might be the easy part.

On Monday night, to no one's surprise, he declared his candidacy at a rally in Miami, Florida. In the weird world of American politics, the front-runner in the polls was already deemed to be falling behind. The campaign launch was a relaunch. It was therefore crafted to display Mr Bush's understanding of why his party has lost the popular vote in five of the last six presidential elections.

In a hall in a predominantly Cuban-American district, before a 3,000-strong audience described reflexively by the American media as "diverse", he brought on salsa musicians, an African-American pastor and a Colombian-American advocate for disabled children. It was as though to say: "These are the people who spurn the Republican Party. And I can fix that."

So much remains to be seen. Reportedly, the proceedings in Miami were interrupted just once, by a group who dislike Mr Bush's immigration policy and who wore T-shirts with the slogan "Legal Status is Not Enough". The moment encapsulated one of the candidate's problems. On his own side, within the so-called Republican base, he is detested precisely because he would grant "amnesty" to certain illegal immigrants.

His rivals for the nomination will make much of that alleged weakness all the way to the Republican convention in Cleveland, Ohio, next summer. For now, as though to remind the world of how fragmented conservatism has become in the US, Mr Bush will have to see off - according to the Politics and Governance Portal - 31 rivals who are either declared or "exploratory" candidates. Yesterday, Donald Trump decided to add to the gaiety of his nation by ending his explorations and issuing his declaration.

Mr Bush, with $100 million already raised, will trounce most of the contenders in short order. Even some deemed serious will barely start the course at the Iowa caucus and the New Hampshire primary next February, far less stick with it.

But the presence of Scott Walker of Wisconsin, Marco Rubio from Florida, Rand Paul of Kentucky, Ted Cruz from Texas, and former Arkansas Governor Mick Huckabee - with any wild cards that spring up - point in one direction: today's Republican Party scarcely has an identity, far less a purpose.

Such is the challenge for John Ellis ("Jeb") Bush. If he has a $100m down payment ready, he means to win. To whom does he appeal? The remnant Tea Party? The fragmented Christian right? The social conservatives or the social liberals? Those obsessed with halting immigration or the children of immigrants? Those who regard the candidate's "bicultural" marriage to the former Columba Garnica de Gallo from Leon, Mexico, as a testament to modern American realities, or those clinging to the old, white world?

It is probably impossible to put the Republican base back together. Mr Bush's campaign managers have no doubt consoled him with the fact that it doesn't much matter if he can only win the nomination. Just before the 2012 election, 40 per cent of voters identified themselves to Gallup as "independent". The idea Mr Bush will have to please every shade of conservative opinion is mistaken. Nevertheless, he will still have to stand before America and define his version of Republican.

Forget Democrats: a horde within his own party will interrogate his every utterance. Then forget the pack of party rivals: ordinary Americans will want to know about the candidate's claims to have wrought an economic miracle while governor of Florida between 1999 and 2007. They will want to know what he really thinks about immigration, the environment, and the "Common Core" educational reforms of which he boasts. Above all, they will want to know why the Bush family thinks it is entitled to provide a third president in two generations.

A country with a habit of boasting about its democratic credentials is none too fussed, it turns out, over the advent of a political aristocracy. A Washington Post poll in January found that only 14 per cent would be less likely to vote for a candidate named Clinton. The name Bush produced a stronger reaction - a third expressed scepticism - but still the majority didn't care. Dynasties trouble Americans less than the rivers of money flowing through public life, and no one has been able to solve that problem.

Nevertheless, the idea that still another Bush believes himself uniquely suited to run the country worries just enough people - people who are not registered Democrats, that is - to give the candidate's handlers concern. On Monday, he tried to deal with the issue by asserting: "Not one of us deserves the job by right of resume, party, seniority, family, or family narrative. It's nobody's turn. It's everybody's test, and it's wide open."

He might have added: "So you won't be seeing much of my brother George". President 43 is these days no one's hero, least of all among right-wingers in his adopted state of Texas. For other Americans more profound questions hang over the clan. Asked recently whether, given present knowledge, he would have invaded Iraq in 2003, Jeb Bush took fully four days, amid endless "clarifications", to come up with an answer. (In the end, yes became no.)

Was that confusion born of dynastic loyalty? Will Hillary Clinton, in turn, deal honestly with her husband's legacy amid a welter of claims involving his foundation, foreign donors, and certain decisions she took while Secretary of State? It seems unlikely. America's cherished democratic contest increasingly resembles a struggle between brand names and political machines.

Ideologically, the US remains the divided "50-50 nation", still fighting the culture wars that have spread, now, even to the bastions of conservatism. Whatever else he has managed to prove, Barack Obama has demonstrated that even the semblance of unity is hard to find in such a nation. How could a pair of dynasts, with all their family baggage, possibly help?

Mr Bush has a way to go before he can begin to answer the question. Rather than ask why he is fit to be president, you could ask why this individual can rustle up $100m as political seed money, or why Mrs Clinton is aiming to raise a reputed $2 billion, a sum she expects to be matched by those who will anoint the Republican nominee. The new dynasties are powerful, but in essence they, like their famous names, are just window-dressing.

None of this has much to do with what the Tea Party meant by "reclaiming America". It's not what hopeful migrants think is meant when the Oath of Allegiance is administered. Jeb Bush is another plausible face with a familiar name groomed play the part of President. The more startling fact is that he is far from the worst that his confused and resentful party has to offer.

President Trump? The other sound you hear is Thomas Jefferson turning in his Monticello grave.