(CNN) Here's a concept new to the 2016 campaign: Donald Trump and détente.

Trump, who built a campaign on lambasting Republican elites, Thursday came to the citadel of the political establishment -- Capitol Hill -- for a summit with House Speaker Paul Ryan and other party leaders designed to halt the GOP's self-immolation.

From the moment the billionaire's Boeing 757 rolled to a stop to the moment when it lifted into the steel gray skies over Ronald Reagan National Airport nearly six hours later, he whipped up an extraordinary spectacle -- perhaps a taste of what is to come if he is elected president.

It was a day, as CNN's Senior White House Correspondent Jim Acosta put it, that was about Republicans beginning to build a "tent big enough for the circus that you have seen roll into town."

The Capitol Dome -- glistening white in its newly restored state -- has known generations of political drama but can rarely have witnessed such a media carnival-- as GOP leaders sat down to talk a truce with the ringleader of their rebellious grassroots.

At the end of the day, there was a general feeling that after the recriminations of a bitter primary season -- things had gone rather better than many people expected.

"While we were honest about our few differences, we recognize that there are also many important areas of common ground," Ryan and Trump said after their meeting -- which lacked a grip-and-grin photo-op but was described by both sides as a good start.

"We will be having additional discussions, but remain confident there's a great opportunity to unify our party and win this fall, and we are totally committed to working together to achieve that goal."

The statement included a concession to Trump -- a recognition that he had brought millions of new voters into the Republican fold.

But it also inadvertently hinted at the distance that still remains when the statement talked about unification of the party -- a word more often employed to refer to mending nations carved in two by manmade walls, like the Koreas or Cold War-era Germany.

Still, one senator told CNN's Manu Raju that the meetings had gone well and that the voluble billionaire let others do the talking.

"They actually kind of liked him," the senator said, who asked not to be on the record.

There was one significant piece missing from the day of Republican healing — a formal endorsement of Trump by Ryan. But the speaker left the impression that such a step could happen if follow-up meetings designed to drill into the "weeds" of policy differences between the two men go well.

Trump and Ryan had raised the stakes for the talks themselves -- especially after the Speaker last week said in a bombshell CNN interview that he was not ready to endorse the fiery presumptive GOP nominee, who later complained that he was blindsided.

For once -- Trump, though the center of attention, did not contribute to the political cacophony himself, contenting himself with the Ryan statement and a few Tweets.

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Reporters only glimpsed him fleetingly, as he stepped out of his Secret Service SUV to offer his distinctive gesture: a wave from his much-commented-upon hands becomes a thumbs up.

"Great day in D.C. with @SpeakerRyan and Republican leadership. Things working out really well! #Trump2016," the presumptive nominee tweeted as his jet taxied to the runway as he left town.

Mr. Trump came to Washington followed by a huge media pack, and his visit recalled the wall-to-wall coverage last seen when Pope Francis was in town last year.

Adding to the spectacle: Bagpiper Ben Williams, who played at Justice Antonin Scalia's funeral, played "Amazing Grace" outside the Republican National Committee headquarters in a bid to foster feelings of unity, while protestors, including one wearing a massive papier mache head of Trump, picketed the meeting and a CodePink protestor held a banner reading "Trump is a racist."

In some ways, Thursday was the first step in a transfer of power.

Ryan is the man who, as the top-ranking Republican in the U.S. government, has been effectively the Republican Party leader in a turbulent period and has framed an alternative, conservative, agenda to Trump's to safeguard his House majority.

But once Trump finishes piling up the 1,237 delegates he needs to secure the Republican nomination, he will become the face of the party -- and lead it back to power in the White House or consign it to another four years in the wilderness.

Given the vast policy gulfs between Ryan and Trump -- on issues like entitlements and budgets -- and the Speaker's evident discomfort with Trump's rhetoric on Muslims and other issues, there appeared plenty of scope for things to go wrong.

"Look, it's no secret that Donald Trump and I have had our differences. We talked about those differences today. That's common knowledge," said Ryan when he emerged from the talks -- sounding like someone forced to explain a first date in front of a room of reporters straining for every detail.

"I met him for 30 seconds in 2012. So, we really don't know each other," Ryan said.

A reporter asked: "What did you think of his personality?"

"I thought he has a very good personality. He's a very warm and genuine person."

In many ways, Trump and Ryan could hardly be more different, so the speaker is probably right when he says it will take "more than 45 minutes" to forge a bond.

Ryan, an observant Catholic, is one of the most self-disciplined politicians around -- with his devotion to his P90X fitness regimen and love of plunging into the depths of a government budget.

Trump, by contrast, might be the least-constrained politician ever to win a major party nomination -- with his often inflammatory rhetoric and rudimentary policy positions, several of which have evolved in recent days.

Ryan was not the only leader who Trump met Thursday. Reince Priebus, the RNC chairman, played matchmaker in the talks between the speaker, his follow Wisconsinite, and the presumptive nominee.

Priebus told CNN's Dana Bash the meeting was "great" and that there was good chemistry between Trump and Ryan.

And Trump also saw Republican Senate Majority leader Mitch McConnell, who has already offered him a lukewarm endorsement. The billionaire later tweeted out a black-and-white picture of the pair in animated conversation, with Trump staring down at the Kentucky senator in an LBJ-like pose.

And Trump requested, and got, a meeting with the ultimate Republican establishment fixer -- former secretary of state and Treasury secretary James Baker.

It was all too much for Harry Reid, McConnell's opposite number in the Senate, who provided the Democratic commentary for Trump's Capitol Hill visit.

"Since Senator McConnell is so enthusiastically embracing Trump, we can only assume he agrees with Trump's view that women are dogs and pigs," Reid said, in his characteristic undertakers' tones.

But Reid's stunning intervention was only one eye-popping moment of a bizarre day in American politics -- the likes of which has become more and more common in the age of Trump.

A few miles away from the hubbub, Washington Post columnist Dana Milbank was consuming a nine-course meal made up of his previous columns, as he lived up to a vow to eat his words if Trump won the Republican nomination.

And on the other side of the country, in South Dakota, Democratic presidential candidate Bernie Sanders was visiting Mount Rushmore -- perhaps sizing up real estate for the future -- as he pursues a campaign few people believe will end in success.

Meanwhile back in the Mansfield Room of the Senate, Republican senators sat down for their weekly conference and were forced to 'welcome' back one of their least favorite colleagues, Ted Cruz, a week after the Texas senator abandoned the presidential campaign trail.

"To be honest with you, I didn't want to come back," Cruz said, according to a senator in the room.

Sen. John McCain, who once branded Cruz a "wacko bird," responded with gallows humor: "We didn't want you to, either."