If anything could have sweetened Donald Trump's triumphant return on Friday to centre stage at the Conservative Political Action Conference, it might have been the sour reception he received there in the past.

Two years ago, he was booed at the mention of bringing U.S. "boots on the ground" to Syria. At CPAC 2016, he opted to bail on the annual gathering altogether. So thin were his chances, conservatives believed then, that a presidential straw poll put him in third place, behind senators Ted Cruz and Marco Rubio.

Watch: Trump gets booed at CPAC in 2015:

How things have changed.

On Friday, the new commander-in-chief commanded standing ovations.

In his CPAC address, Trump returned to familiar themes, doubling down on attacking the "fake news media" as the "enemy of the people" — a remark followed hours later by the White House blocking CNN, the New York Times and other media outlets from a press briefing.

But the president played coy on Friday about his no-show in 2016.

"I would have come last year, but I was worried that I would be too controversial," he teased an adoring CPAC audience.

"Now, you finally have a president. Finally. Took you a long time."

It was only a year ago January that the influential conservative publication the National Review published its collected "Conservatives Against Trump" essays.

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Supporters shout down a protester as the president speaks at the conference Friday. (Alex Brandon/Associated Press)

At CPAC in 2016, he was brushed off as the "pro-choice, Democrat-donating" candidate who was far from becoming the next darling of the conservative movement, said veteran Republican political consultant Jarryd Gonzales.

This year, elated attendees cheered on Trump's big-spending promises — for infrastructure, the military and a pledge to build a border wall with Mexico to the tune of a projected $20 billion — the kinds of promises that might ordinarily clash with conservative orthodoxy.

Not a 'traditional conservative'

"You have to remember Trump is not your traditional conservative," Gonzales said. 

But if he can convince his party he has enough popular support for his big ideas, he may be able to push his agenda through. "CPAC is part of Trump's political playbook," Gonzales said.

Loud as the crowds in their "Make America Great Again" hats were, the silence from prominent congressional Republicans who skipped out on the annual meeting of conservative power brokers was just as notable. House Speaker Paul Ryan was reportedly absent, as were Senate majority leader Mitch McConnell and senators Rubio and Rand Paul, considered perennial CPAC guests.

When Trump again blasted the North American Free Trade Agreement in his speech as "one of the worst deals" the U.S. has ever made, the applause might have sounded like a death knell for Reagan-era conservatism.

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Supporters cheer President Donald Trump as he speaks at the Conservative Political Action Conference (CPAC), Friday, Feb. 24, 2017, in Oxon Hill, Md. (Alex Brandon/Associated Press)

Trump's free-market-averse speech was not something Mac Stipanovich, a #NeverTrump Republican analyst, recognized as the fiscally responsible values CPAC is known to push.

"There was a day when conservatives were concerned about fiscal conservatism and ballooning deficits. That day is apparently over."

It may be called CPAC, "but the 'C' doesn't stand for 'conservative' anymore," Stipanovich said. "It stands for 'collaborators' — people who are abandoning their principles to be on the winning side."

'Sore winner'

Prominent Trump spokesperson Kellyanne Conway promised this year's CPAC would look more like a "TPAC," in honour of Trump's victory.

And in case anyone forgot that, his speech Friday was laced with references to the polls and his Democratic detractors Hillary Clinton and Bernie Sanders.

"Our victory was a win like nobody has ever seen before," Trump said, still basking in the three-month-old afterglow of his election victory.

Stipanovich's reaction: "He's the first sore winner in American presidential history."

In a return to the campaign-style speeches, Trump championed "America First" governing over a "global flag" agenda. He walked off stage to the same song he played while stumping: The Rolling Stones' You Can't Always Get What You Want.

But there's a cost to staying in campaign mode, said presidential historian Mike Purdy. For one thing, it risks impeding the job Trump fought for in the first place.

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This 2011 photo shows Donald Trump addressing the Conservative Political Action Conference back when he was little more than a curiosity and the brash billionaire star of reality TV's The Apprentice. (Alex Brandon/Associated Press)

"The tweeting, the speaking, the campaigning — is it at the expense of governing? At this point, yes," Purdy said. "But we have to remember that Trump has a steep learning curve to get his arms around what is involved in managing the federal government." 

The nation's chief executive is acting more like a "chairman of the board" than a hands-on "CEO," said Purdy, who curates the Presidential History Blog and is working on a book about the 2016 election campaign

"Trump is not particularly a details guy."

Dissonance with rank-and-file Republicans is showing. Ryan's memo for fixing the Affordable Care Act, for example, remains mired by sticking points including reforms to Medicaid and replacing Obamacare subsidies with tax credits. A replacement now looks to be at least a year away.

But Trump was off-message, tweeting last week that progress regarding the health care law was "moving fast."

The most unpopular president in the history of early-term polling, with just 38 per cent approval, continues to retreat to his base supporters. Last week, he boarded Air Force One for what White House press secretary Sean Spicer described as a "campaign" rally in Florida.

Trump revealed he has already coined his 2020 presidential slogan, requesting that his lawyers trademark a new phrase: "Keep America Great."