There was a "Mission Accomplished" feel to the beginning of President Joe Biden's first stop in Boston Monday, at Logan Airport's still-uncompleted Terminal E, which got a big funding boost in last year's Bipartisan Infrastructure Law.

Before Biden spoke, a steady stream of Massachusetts Democrats stepped to the podium and paid tribute to the same approach to government. The particulars differed, from Boston City Councilor Gabriela Coletta to Sens. Elizabeth Warren and Ed Markey, but the gist was the same. Essentially: smart public spending creates jobs, improves quality of life, increases climate-change readiness and boosts the economy — the implication being that since Biden and Democrats are currently getting this stuff right, they deserve voters' backing in the midterms and beyond.

Oddly, it was Biden who took the triumphalism down a notch. He didn't disagree with those premises, or with the idea that Democrats are getting results. In fact, Biden said, a host of new evidence — including falling gas prices, falling inflation rates and the recent opening of a new computer-chip plant in Ohio — show that Democratic policies are working quite well.

But Biden also made it clear that, in his analysis, good policies and good outcomes alone aren't nearly good enough. What's needed, he said, is American ambition, a combined sense of ability and possibility the nation has lost.

"Go back to the way your mother or father would explain to you what America was like 50 years ago," Biden said toward the end of his Logan speech. “There's no question: there wasn't a damn thing we couldn't do if we set our mind to it.

"The American people, because of our failure to think big, in my view, have begun to wonder: You know, can we really do anything?" Biden added. "How much can we really do? Are there any things that are significant that America can do better than any country in the world?"

Enter Biden's "cancer moonshot" — which just happened to be the topic of his second appearance in Boston. A few hours after appearing at Logan, Biden spoke at the John F. Kennedy Presidential Library and Museum in Dorchester, 60 years to the day after JFK gave a legendary speech at Rice University in Texas calling for America to win the space race with Russia.

Cancer, as Biden reminded the audience at his Dorchester speech, is an intensely personal issue for him. His son Beau died of it, and like many grieving parents, Biden seems to have locked in on the force that took his child's life as a nemesis to battle. But Biden also told the crowd in Dorchester that cancer is — or in his estimation, should be — precisely the sort of foe that can inspire Americans to put their political differences aside and pursue world-altering goals.

"Cancer does not discriminate [between] red and blue," Biden said. "It doesn't care if you're a Republican or a Democrat. Beating cancer is something we can do together, and that's why I'm here today."

There's something almost painfully poignant about Biden's dream of leveraging the disease that killed his child to unify a fractured nation. But while cutting cancer deaths in half in the next 25 years may be a praiseworthy goal, there are some weaknesses to his pitch.

The first is that Biden's cancer moonshot is not, technically, a new idea: as he reminded the audience in Dorchester at some length, it was launched under President Barack Obama and has been brought back, in various institutional and legislative ways, throughout Biden's administration. Novelty is a power political force, and right now, the "moonshot" doesn't really have it.

An even bigger problem is that, despite Biden's professed desire to look to the future, his appeal to America's once-strong sense of exceptionalism is inherently nostalgic. He's not just calling on Americans to meet a new challenge; he's calling on us meet a new challenge, just like a now-revered president did several decades ago, with an explicitly stated desire to get us now thinking more like Americans of a previous era.

There's a structural issue worth highlighting, too. Biden's "moonshot" needed to be launched in his presidency because it effectively ceased under former President Donald Trump — not because cancer discriminates between Republicans and Democrats (Biden's right, it doesn't), but because in the nation's current political reality, virtually everything has the potential to become a partisan issue.

Imagine Biden’s cancer push yielding big results for the duration of his current term in office. Then imagine Biden losing in 2024 to Trump, Florida Governor Ron DeSantis or any other Republican. Ask yourself: what are the odds the “moonshot” would actually continue after the next administration was in place? Right now, the idea of unifying the country behind a shared sense of American exceptionalism is a tough sell, no matter how commendable the end goal may be.