For all you knuckleheads on Fox who say that Biden can’t put two sentences together, here’s a news flash: He just put NATO together, Europe together and the whole Western alliance together — stretching from Canada up to Finland and all the way to Japan — to help Ukraine protect its fledgling democracy from Vladimir Putin’s fascist assault. In doing so, he has enabled Ukraine to inflict significant losses on Russia’s invading army, thanks to a rapid deployment of U.S. and NATO trainers and massive transfers of precision weapons. And not a single American soldier was lost.

It has been the best performance of alliance management and consolidation since another president whom I covered and admired — who also was said to be incapable of putting two sentences together: George H.W. Bush. Bush helped manage the collapse of the Soviet Union and the reunification of Germany, without firing a shot or the loss of a single American life.

Alas, though, I left our lunch with a full stomach but a heavy heart. Biden didn’t say it in so many words, but he didn’t have to. I could hear it between the lines: He’s worried that while he has reunited the West, he may not be able to reunite America.

It’s clearly his priority, above any Build Back Better provision. And he knows that’s why he was elected — a majority of Americans worried that the country was coming apart at the seams and that this old war horse called Biden, with his bipartisan instincts, was the best person to knit us back together. It’s the reason he decided to run in the first place, because he knows that without some basic unity of purpose and willingness to compromise, nothing else is possible. But with every passing day, every mass shooting, every racist dog whistle, every defund-the-police initiative, every nation-sundering Supreme Court ruling, every speaker run off a campus, every bogus claim of election fraud, I wonder if he can bring us back together. I wonder if it’s too late.

I fear that we’re going to break something very valuable very soon. And once we break it, it will be gone — and we may never be able to get it back. I am talking about our ability to transfer power peacefully and legitimately, an ability we have demonstrated since our founding. The peaceful, legitimate transfer of power is the keystone of American democracy. Break it, and none of our institutions will work for long, and we will be thrust into political and financial chaos. We are staring into that abyss right now. Because it is one thing to elect Donald Trump and pro-Trump candidates who want to restrict immigration, ban abortions, slash corporate taxes, pump more oil, curb sex education in schools and liberate citizens from mask mandates in a pandemic. Those are policies where there can be legitimate disagreement, which is the stuff of politics.

But the recent primaries and the investigations around the Jan. 6 insurrection at the Capitol are revealing a movement by Trump and his supporters that is not propelled by any coherent set of policies, but rather by a gigantic lie — that Biden did not freely and fairly win a majority of Electoral College votes and therefore is an illegitimate president. Thus, their top priority is installing candidates whose primary allegiance is to Trump and his Big Lie — not to the Constitution. And they are more than hinting that in any close election in 2024 — or even ones that aren’t so close — they would be willing to depart from established constitutional rules and norms and award that election to Trump or other Republican candidates who didn’t actually garner the most votes. They are not whispering this platform. They are running for office on it.

In short, we are seeing a national movement that is telling us publicly and loudly: WE WILL GO THERE. And that terrifies me because: I HAVE BEEN THERE. My formative experience in journalism was watching Lebanese politicians go there in the late 1970s and plunge their frail democracy into protracted civil war. So don’t tell me that it can’t happen here. Not when people like Pennsylvania State Senator Doug Mastriano — an election denier who marched with the Jan. 6 crowd at the Capitol — just won the G.O.P. primary to run for governor. Have no doubt: These people will never do what Al Gore did in 2000 — submit to a decision of the courts in an extremely close election and recognize his opponent as the legitimate president. And they will never do what principled Republicans running for office or acting as elections officials did after the 2020 election — accept the votes as they were tabulated in their states, accept the court orders that confirmed that there were no significant irregularities and permit Biden to legitimately take power.

It is stomach-turning to watch the number of Trump Republicans running for office affirming his Big Lie, when we know that they know that we know that they know that they do not believe a single word of what they are saying. That’s Dr. Oz and J.D. Vance and so many others. Nevertheless, they are ready to hitch a ride on the Trump train to gain power. And they do it without even blushing. It reached its nadir, in my view, when House Minority Leader Kevin McCarthy, so obsessed with becoming speaker of the House at any cost, actually lied about telling the truth. McCarthy publicly denied the fact that immediately after Jan. 6 he explicitly (and on tape) told his Republican colleagues that he expected Trump to be impeached for inspiring the insurrection and that McCarthy intended to tell him he should resign. Who in your life have you ever encountered who lied about telling the truth?

And this brings me back to my lunch with Biden. It clearly weighs on him that we have built a global alliance to support Ukraine, to reverse the Russian invasion and to defend core American principles abroad — the right to freedom and self-determination of all peoples — while the G.O.P. is abandoning our most cherished principles at home. That is why so many allied leaders have privately said to Biden, as he and his team have revived the Western alliance from the splintered pieces that Trump left it in, “Thank God — America is back.” And then they add, “But for how long?”

Biden cannot answer that question. Because WE cannot answer that question.

Biden is not blameless in this dilemma, nor is the Democratic Party — particularly its far-left wing. Under pressure to revive the economy, and facing big-ticket demands from the far left, Biden pursued expansive spending for too long. House Democrats also sullied one of Biden’s most important bipartisan achievements — a giant infrastructure bill — by making it hostage to other excessive spending demands. The far left also saddled Biden and every Democratic candidate with radical notions like “defund the police” — an insane mantra that would have most harmed the Black and Hispanic base of the Democratic Party had it been implemented.

To defeat Trumpism we need only, say, 10 percent of Republicans to abandon their party and join with a center-left Biden, which is what he was elected to be and still is at heart. But we may not be able to get even 1 percent of Republicans to shift if far-left Democrats are seen as defining the party’s future.

And that is why I left my lunch with the president with a full stomach but a heavy heart.