(CNN) Sen. John McCain's heroism and code of honor, duty and unifying pragmatism will endure as a powerful historical example . But his political legacy met its match in President Donald Trump, who has prevailed in their struggle for the current soul of the GOP.

As the 2008 Republican presidential nominee leaves the stage, the trajectory of his party is ever more aligned with the worldview and combative attitudes of Trump, who electrified the party's activist base in a way McCain could never manage.

There is no sign that grass-roots conservatives are about to return to the loftier, more traditional views embodied by McCain -- even as he is being lauded in the political world as a paragon of self-sacrifice and patriotic service. It's quite clear that the GOP base prefers Trump's scorched earth politics and attacks on political institutions and traditions that McCain revered.

In primary races across the country, including in McCain's Arizona, which goes to the polls on Tuesday, GOP candidates have been replicating the President's style and insurgent narratives, forcing more moderate candidates to tack to the right to keep their campaigns alive.

Their behavior reflects the reality that Trump won the Republican nomination in 2016 largely because he was so unlike the Arizona senator and other more temperate Republicans, such as Florida's Sen. Marco Rubio, or establishment scions such as former Florida Gov. Jeb Bush.

In one final appeal, McCain delivered a last jab at Trump's America First ideology, which has usurped his Ronald Reagan-style internationalism, in a farewell message read out by his former campaign manager Rick Davis on Monday.

"We weaken our greatness when we confuse our patriotism with tribal rivalries that have sown resentment and hatred and violence in all the corners of the globe," McCain told his fellow Americans

"We weaken it when we hide behind walls, rather than tear them down, when we doubt the power of our ideals, rather than trust them to be the great force for change they have always been."

McCain did not directly mention Trump but everyone knew what he meant.

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The depth of the antipathy between McCain and Trump played out as Washington got back to work for the first time since the passing of one of its most high-profile statesmen.

Three times on Monday, Trump crossed his arms, set his jaw and simply ignored questions from reporters about McCain's legacy, following his failure to issue even a written statement paying tribute to his foe, the very least that would be expected of a President.

It was a reminder that Trump shows few signs that he views the presidency as a national trust that sometimes must take priority over his own immediate political interests.

He ordered flags to half-staff on government buildings until McCain's burial on Sunday, after the Stars and Stripes at the White House was earlier returned to the top of its pole in a move that sparked a backlash in Washington.

Then, in remarks to evangelical leaders, the President said that "we very much appreciate everything Sen. McCain has done for our country."

Farewell to McCain's brand

But if McCain's camp can claim a final moral victory for the senator over the President, it's also clear that Washington is not just mourning a statesman, it is also saying farewell to his brand of politics.

Senate Majority Leader Mitch McConnell offered a moving address, praising McCain as a national hero "integral to the United States Senate."

But he did not mention the great legislative campaigns that McCain will be most remembered for, including his bipartisan pushes on immigration and campaign finance legislation or his crusade to ban the torture of terror suspects.

That's because the Republican Party, with its march to the right, has largely rejected such policies.

In other areas, including his support for free trade, his revulsion for Russian President Vladimir Putin and global strongmen, his vehement support for the Atlantic alliance and human rights, McCain found himself at odds with a President who has an iron grip on his party.

Even in his affection for the press, the Arizona senator enraged Trump voters.

McCain's increasingly outspoken attacks on the President in the final months of his life cemented his decline among the party's grass roots.

In a CNN/ORC poll in October 2013, 56% of Republicans said they had favorable opinions of McCain, compared with 45% of Democrats.

By this June, a CNN/SSRS survey found the situation reversed, with only 33% of GOP voters approving of McCain, compared with 67% of Democrats. Only 32% of those who approved of Trump also liked McCain.

At the same time, there is no doubting Trump's hold on the GOP of 2018. An NBC/Wall Street Journal poll released on Sunday put his approval rating among Republicans at 90%.

That data explains why Trump's insulting behavior toward McCain, though drawing disgust in Washington, is unlikely to exert a political price. It's a lesson Trump intuited in 2015 when he said the Vietnam War veteran was not a hero because he had been captured.

It's also a reason why the President's absence from McCain's memorial service at Washington's National Cathedral on Saturday -- at the request of the senator's family -- might be a personal humiliation, but will contain a certain amount of political vindication.

After all, being shunned by the biggest gathering in months of Washington elites plays directly into Trump's insurgent narrative.

Many grass-roots Republicans have long been suspicious of McCain, whose ideological unorthodoxy grated on some conservatives as far back as his 2000 presidential primary race against George W. Bush. In 2008, there was a noticeable enthusiasm gap among Republicans who attended riotous rallies by his running mate, Sarah Palin, and staid events featuring the GOP nominee himself.

In retrospect, his selection of Palin was a first warning sign of the tea party revolt that would rock the GOP several years later, which led to a full-scale Trump revolution and has culminated in the eclipse of more moderate conservatives in the party such as McCain, his fellow Arizonan Sen. Jeff Flake and Tennessee's Sen. Bob Corker, all of whom will be gone when the new Congress convenes next year.

'Savaging' Trump

The conservative media offers a reminder that while McCain was adored in Washington, by his colleagues and the reporters who covered him, the outpouring of grief at his passing is not necessarily shared by Republicans in the heartland.

Many conservatives see such coverage as just another opportunity for the media to condemn Trump by implication.

"One of the reasons there's reverence for McCain is the opportunity it provides to continue to savage Donald Trump, to continue to rip Donald Trump by setting up these comparisons between Trump and McCain and showing Trump coming up short on virtually every measure the drive-bys (mainstream reporters) make," Rush Limbaugh said Monday on his radio show.

If there is a lesson McCain wanted to send at the end, it is that the GOP under Trump has taken a turn away from fundamental American values.

"We argue and compete and sometimes even vilify each other in our raucous public debates. But we have always had so much more in common with each other than in disagreement," he wrote in his farewell message.

But many conservatives in the early 21st century -- suspicious of establishment institutions and mainstream political leaders -- simply do not see the world that way.