In the latest polls, Donald Trump is still leading the field of Republican presidential contenders, far ahead of Jeb Bush and very close to Hillary Clinton among voters in swing states.

How come? What forces have propelled Trump up and over our political establishment?

There is a simple answer that has eluded our pundits: Donald Trump is the Andrew Jackson of our time.

Jackson was the frontier populist who in the 1820s and 1830s took on the financial elite of Boston, New York and Philadelphia. As president, he took down the effete Nicholas Biddle and the Second Bank of the United States.

Jackson, like Trump, was proud of owing nothing to anybody. He was always ready to fight, like most of those who lived west of the Appalachian Mountains and in the hills of the South. He was a man's man who spoke common-sense truth to power.

Jackson spoke for those who sought the American dream through sweat — the middle class of his day.

The Jeb Bush of Jackson's time was John Quincy Adams, accomplished scion of a leading political family. Jackson beat him at the polls in 1828. And to celebrate his first inauguration, Jackson opened the White House to hordes of "the people," who promptly got drunk and broke the china.

To break up continued rule by the Eastern elite, Jackson replaced sitting officials with his own choices, initiating what became the "spoils system" — a populist mechanism of tribal loot-sharing soon institutionalized by political machines.

Jackson was a tribal leader, defending the interests of the tribe of white Americans against alien cultures such as the perfidious British and Native Americans.

Under Jackson's Indian Removal Act of 1830, tribes such as the Cherokee were forced from their homes and sent to the Indian Territory west of the Mississippi, a policy that today would be called ethnic cleansing. Jackson appointed Roger Taney as Chief Justice of the Supreme Court. Taney would later rule that Dred Scott, a black man, could not be a citizen and that slavery was to be permitted throughout the U.S. Jackson's white tribalism was to be defended at all costs.

Trump's politics echo Jackson's. Trump's tax plan is Jacksonian — seeking to reduce taxes for the "yeomanry" and raise them on the Nicholas Biddles of our time, who make their money from playing with other people's money.

Trump's taking on sacred cows of the establishment, such as John McCain's heroism for being captured and political correctness toward illegal immigrants and women journalists — even his challenging of the law of the land granting birthright citizenship — is all very like Jackson, who indiscriminately railed away at those who considered themselves his social superiors.

Trump's inner compass points him to a role as warrior chieftain of his tribe. He relishes being a blunt-spoken tribal leader who always has his dukes up to protect his kith and kin from abuse and marginalization. Trump's campaign manifesto is to be called "Crippled America."

Like Jackson, Trump echoes from a distant past and the tribalism of William Wallace of "Braveheart" fame. Jackson was indeed Scots-Irish by birth; Trump's mother was born in Scotland.

When you hear "the Donald" bluster, recall Mel Gibson's call to his warrior followers to defend their "freedom" from their English overlords and feel the emotional powers propelling Trump up in the polls.

To contemplate the impossibility of Jeb Bush ever becoming such a heroic persona is to understand why Bush is out of sync with the white tribe in our times. That tribe of mostly middle-class families feels put upon and abandoned by the country's leaders.

Trump's challenge is to expand his tribe beyond its existing membership, which is only a large plurality of whites. How can he bring into tribal good-standing African-Americans, Hispanics and Asians? And can he ever re-engage those white women who have been "detribalized" in recent decades by the feminist understandings of gender?

Perhaps he can throw the mantel of his protective patronage over a wider constituency using economic policies — because Trump truly is a populist, not a traditional Republican.

The last time the Republican Party split into populist and establishment camps was in the Gilded Age of great inequality of wealth, when Teddy Roosevelt promoted progressive policies to help the "little man" against "malefactors of great wealth."

Though born to establishment wealth and comfort, Roosevelt too presented himself as rough and ready in Jackson's image — the frontiersman and big-game hunter, fearless commander of the Rough Riders.

We have, in short, been in Trump's cultural territory before.

Stephen B. Young, of St. Paul, is global executive director of the Caux Round Table, an international network of business leaders working to promote a moral capitalism.