Nic Robertson is CNN's international diplomatic editor. The opinions in this article belong to the author.

(CNN) If Europe's leaders, diplomats and security professionals had a vote in the 2020 US presidential elections, it doesn't seem likely they'd give it to President Trump. At least, that's how it seemed at the 2019 Munich Security Conference .

Hundreds of dignitaries crammed into tight corridors, moving between the modest meeting halls of Munich's Bayerischer Hof Hotel.

The event has grown in recent years. As prime ministers and presidents rub shoulders with CEO's and policy wonks, conversations straddle global differences and attempt to shape the world order.

It is an odd, almost old-fashioned mix. It's rare at global summits these days that reporters can mingle with the people they cover and even engage them in casual conversation.

NATO Secretary-General Jens Stoltenberg surprised me, praising my sturdy weather-beating boots and trousers. He laughed when I told him he was lucky inside. I was outside, the sun was blazing and, frankly, I was baking.

This year I saw the greats of the Obama-era Iran nuclear deal breeze between meetings in a way impossible at the height of those negotiations.

Yet a few years later, their sage experience is the valued currency of many backroom conversations.

John Kerry's sidekick, Wendy Sherman, strolled down the street past former US Energy Secretary Ernest Moniz, also a member of the Iran nuclear deal negotiating team. He was loitering on a street corner waiting for a car. If you had a question for them, you could ask it.

These people are the unseen grease in the cogs of international diplomacy.

But the showstopper at the conference was the Yin and Yang of US foreign policy -- delivered by Vice President Mike Pence and the guy who had the job before him, Joe Biden.

JUST WATCHED 2020 Democrat rankings: Biden up, Beto down Replay More Videos ... MUST WATCH 2020 Democrat rankings: Biden up, Beto down 01:36

They spoke on the same day, but could not have been more different in tone, style and substance.

Pence channeled a forceful, direct Trump. Biden's overnight flight hung heavily on him.

Pence could have been better prepared, had his speech writer more carefully gauged his audience before the vice president stood behind the teleprompter.

A hint at why came the day before, when Nancy Pelosi, Democratic Speaker of the House of Representatives, was introduced to delegates to rapturous applause. That should have been a signal to Pence: he was among allies, not friends.

Pence, clearly hoping for the same warm reception, was instead met with a silent pause when he said he was bringing with him a greeting from Trump.

Pence's pitch was as Trump enforcer, hectoring the gathered NATO allies for underspending and admonishing allies -- the UK, Germany and France -- for refusing to follow the US out of the Iran nuclear deal.

He hadn't come to make friends and he didn't.

Joe Biden, who says he has yet to decide if he'll challenge Trump in 2020, sold himself as the antithesis to Pence and his boss.

"The America I see values basic human decency, not snatching children from their parents or turning our back on refugees on the border."

JUST WATCHED Trump defends declaring national emergency for border wall Replay More Videos ... MUST WATCH Trump defends declaring national emergency for border wall 04:29

He got immediate and huge applause, of the type Pence can only have wished for.

Biden's antidote to Trump's two years was to promise change.

"And I promise you, I promise you. As my mother would say, 'this too shall pass.' We will be back. We will be back. Don't have any doubt about that."

Right on cue more applause fell about him.

No need to guess whom the Munich crowd would put in the White House given the chance.

Two years of Trump has had an impact.

In the hotel this weekend the view is that he is not a safe pair of hands for today's security challenges.

At a presentation titled "NATO at 70: An Alliance in Crisis," two former US representatives to the organization, Douglas Lute and Nicholas Burns, shared insights from its 55 pages. Those insights were garnered, they said, from 60 past and present ambassadors and cabinet secretaries. They concluded that Trump, and his inability to lead, is the biggest of the 10 imminent threats to NATO.

It would be wrong to leave the impression that the Bayerischer Hof Hotel resounded to bays for Trump's departure. It wasn't about him, but his specter hung over it.

Brad Smith, president and chief legal officer of Microsoft and Robert O. Work, deputy secretary of defense under President Obama, gave an electrifying insight to Artificial Intelligence.

"AI is everything," Smith warned, a game changer like electricity. He described the present as a "Sputnik moment."

The former Defense Department official said the "this is the hardest tech challenge the US has ever faced."

Both Smith and Work painted a picture of China chasing, catching and passing the US in this key area. They described AI as an enabler for autocracies like Russia and China and a potential threat for democracies.

In Work's words, "AI gives tyranny new tools it never had before and makes it more powerful than it has ever been before."

No one said it in the room, there was a laser like focus on the intellect and experience of these two men, but at the back of everyone's minds must have been thoughts of Trump's warmth for Presidents Putin and Xi.

Every moment they get cut slack by Trump is more machine code, jacking up their AI programs back home. "We are entering a period intense technological competition," said Work.

In the next war, he predicted, it will be "our AI against their AI, and the side with the best AI wins."

But as much as moments like this came as sobering jabs to the solar plexus, MSC 2019 also held out hope of a world after Trump.

A world this audience warmed to.