Donald Trump is not a friend or ally of the Bush family and its important faction of Republican Party donors and operatives. But in terms of the mass party membership, the shift from the Bush-led party of 2000 and 2004 is less a change in ideology than a shift of points of emphasis.

In an important sense, Trump is following a political trail that W blazed — becoming the first (and so far only) Republican Party politician to follow the template of populist nationalism that the only successful GOP presidential candidate of the past 30 years rode to the White House.

George W. Bush ditched small government ideology — and won

In their signature editorial "Against Trump," the editors of National Review complained that "Trump has shown no interest in limiting government, in reforming entitlements, or in the Constitution" and that Trump's obsession with winning reflects "a spirit that is anathema to the ordered liberty that conservatives hold dear and that depends for its preservation on limits on government power."

Another person who enjoyed winning — at least in the sense of winning elections — was W, who recognized that a big problem with conservatism's philosophical commitment to small government was that it was unpopular.

Consequently:

National Review's editors implicitly concede this when they write that "the Tea Party represented a revival of an understanding of American greatness in these terms [i.e., limited government], an understanding to which Trump is tone-deaf at best and implicitly hostile at worst."

But the whole reason the spirit of limited government required a revival in 2009-'10 is that Bush didn't abide by it. In rejecting the spirit of the Tea Party, Trump is simply recapturing the spirit of a man who (like Trump, so far) was good at winning presidential elections.

Muslims are the new gays

The ugly wave of Islamophobia that Trump has surfed to the top of the polls has naturally provoked comparisons with the extent to which the Bush administration went out of its way to show support for American Muslims. This is usually intended to cast Trump in an unflattering light, and indeed it does.

But to consider the issue through the other lens of the telescope, Trump does not tour the country casting loving gay and lesbian couples as a threat to the American family. He notably refused to join Ted Cruz in attempting to spark a national panic about trans women using the ladies' room.

The rapid speed with which same-sex civil marriage rights became a mainstream cause, then a popular one, then something national that Republicans don't even bother to complain about anymore can lead one to forget exactly how central the issue of "traditional marriage" was to mid-aughts Republican Party politics. But at the time, Bush was warning that "the most fundamental institution of civilization" was under threat from "a few judges and local authorities" who wanted to cast aside "millennia of human experience."

To counter the menace of two people with similar genitalia formalizing their romantic partnership in the eyes of the law, Bush proposed to amend the Constitution. And to maximize the electoral benefit of LGBTQ bashing, Republicans put state-level bans on same-sex marriage (which was not legal, and thus not in need of banning) on the ballot in 11 states to help boost turnout.

The Bush/Trump agenda: tax cuts and nationalism

For all that he was willing to throw money around, Bush was hardly a moderate on fiscal issues. When his presidential campaign launched in 1999, he proposed a large tax cut as a logical response to projected budget surpluses. When he took office in 2001 and those projections evaporated, he pivoted and described the tax cut as a needed fiscal stimulus measure. Then in 2003, he proposed yet more tax cuts — this time described as a long-term growth strategy.

Trump has not bothered to actually offer a reason why his own tax plan would be a good idea, but he does have a tax plan — one of the only issues on which he's bothered to articulate any kind of policy specifics. It's a very Bushian plan, enormously expensive and heavily tilted to the rich, and not articulating a specific reason for it seems just as good as offering multiple, mutually inconsistent ones.

Of course, a political coalition does not live on tax cuts alone. And while indulging in government spending can be smart politics, it offers voters an echo, not a choice.

That's where identity politics and nationalism come in. Instead of pledging to Make America Great Again, Bush nostalgically offered to Restore Honor and Dignity to the White House. Instead of an impractical wall on the US-Mexican border, Bush proposed the construction of a permanent base on the moon. Gays were the internal threat rather than Muslims. French fries were renamed freedom fries, and John Kerry was lambasted for ordering the wrong kind of cheese on his cheesesteak.

Indeed, a key theme of Bush's reelection campaign was that John Kerry spoke French suspiciously well:

Republican Senator Trent Lott of Mississippi recently described Mr Kerry as a "French-speaking socialist." The leader of the Republicans in the House of Representatives, Tom Delay, has been opening his speeches by saying, "Good morning, or — as John Kerry would say — Bonjour." And Commerce Secretary Donald Evans went so far as to accuse Mr Kerry of "looking French", which has become a running joke for Republicans and the hosts on right-wing radio.

These were the key themes of the campaign. Democrats were weak, indecisive, and vaguely foreign — losers, as Trump would say — not insufficiently committed to the precepts of Burke or Hayek.

Under Trump, nationalism turns inward

The big difference between Bush and Trump is that in Bush's schema, American nationalism was mostly projected outward into a vision of global conquest and value spreading, while under Trump it's mostly projected inward and manifests itself as a concern about the influx of immigrants and the need to purge the country of its existing stock of unauthorized migrants.

The Pew Center glossed this divide in its 2014 political typology, which saw Republican Party loyalists as split into two groups, steadfast conservatives and business conservatives. The latter "have generally positive attitudes toward immigrants," while the former feature the lowest level of support for a path to citizenship of any of Pew's groupings. The two conservative groups also "differ over foreign policy," according to Pew:

Steadfast Conservatives have doubts about U.S. international engagement – and view free trade agreements as a bad thing for the U.S. – while Business Conservatives are more supportive of the U.S. taking an active role in world affairs and free trade.

Trump, clearly, speaks for the "steadfast" view here. And it's no surprise that it's catching on. Bush's brand of populist nationalism was extremely politically potent in its heyday. The small problem was that the military adventurism it led to was, in practice, disastrous.

But the connection between American nationalism and assertive engagement abroad is of relatively recent vintage in American history, and historically tied to the specific circumstances of the Cold War. With Islamic radicals clearly not posing any kind of conventional military threat to the United States, but US military involvement in the Middle East bringing frustration rather than glorious victory, a return to the older tradition of nationalism by exclusion is a reasonable thing to try.

This is, obviously, a big difference.

But the key continuity is that Trump realized — in a way that neither Jeb nor Marco Rubio nor the Republican establishment writ large did — that nationalism rather than philosophical commitment to small government is at the core of conservative politics.

The GOP mainstream responded to the failures of Bushism by keeping the same failed foreign policy but trying to ditch the flexibility on spending, even though there's never been any indication that spending money on farmers, oldsters, and schools is unpopular.

Trump, wisely, chose instead to embrace Bush's winning formula and simply pivot the valence of nationalism to better suit our less innocent, more pessimistic times. But if even George W. himself can't figure this out, the rest of the party doesn't have a chance.

Watch: Donald Trump invokes 9/11 while criticizing George W. Bush