The US economy's humming and President Joe Biden is optimistic, but brutal polls and the nation's collective freak-out over a mysterious Chinese balloon will overshadow his State of the Union speech Tuesday.

The Democrat's speechwriters certainly had their work cut out on the weekend as they huddled with the president at the Camp David retreat in the rural hills of Maryland, before flying back to Washington Monday.

A photo posted by Biden on Twitter showed a binder with the speech, a coffee mug and biscuits. "Getting ready," he said.

On arrival back at the White House, Biden told reporters: "I want to talk to the American people and let them know the state of affairs -- what's going on, what I'm looking forward to working on."

But the dramatic downing of a huge Chinese balloon by a US Air Force fighter jet Saturday left the dangerously unstable relationship with the communist superpower literally looming over the Biden administration.

And, as two polls published Sunday and Monday show, well under half of Democrats want 80-year-old Biden to seek a second term in 2024.

In other words, his personal sunniness, embodied by a constant refrain of never having "been more optimistic" about the country, is simply not penetrating.

Just last week, the script for Tuesday's big set piece event -- an address to a joint session of Congress, nearly the entire senior ranks of government, and a vast television audience -- had been almost writing itself.

Inflation, which just a few months ago seemed a near existential threat to the Biden presidency, is steadily ticking downward. Hundreds of billions of taxpayer dollars are starting to flow out into programs passed under Biden to spur high-tech manufacturing and repair infrastructure.

Then on Friday, new figures showed that a surge in job creation has driven unemployment to its lowest rate in 50 years.

In his own mini-preview of the so-called SOTU speech, Biden told journalists: "Next week, I'll be reporting on the state of the union. But today, I'm happy to report that the state of the union and the state of our economy is strong."

Even if Biden has yet to formally announce his 2024 candidacy, the SOTU -- followed by two very campaign-like trips Wednesday and Thursday to Wisconsin and Florida -- is expected to give him a big shove in that direction.

The question now is whether at his age, with an unenthusiastic party, ferociously aggressive Republican opponents, and increasingly Cold War-like confrontations with Russia and China, Biden can push hard enough.

Balloon, but no party?

On his side will be massive advantages: an economy defying multiple predictions of recession and the power of incumbency which means he can spend this year and the next traveling on Air Force One to tout his successes.

But the weekend's news showed what he is up against, even before taking on whomever the Republicans choose as their candidate -- Donald Trump or someone new.

The fighter jet ordered into the sky by Biden efficiently dispatched the Chinese balloon, but the White House faces swirling questions over why the craft -- which China claims was studying weather -- was first allowed to trace a leisurely path across the entire country, passing directly over ultra-sensitive military bases.

And polls show a very down-to-earth danger for Biden: his own side doesn't seem to want him anymore.

In an AP-NORC Center for Public Affairs Research poll, a paltry 37 percent of respondents said they back Biden running for a second term, which would end when he was 86 years old.

In an ABC News-Washington Post Poll, 58 percent of Democrats and Democratic-leaning independents said the party should find someone else for 2024.

Pressed about the disconnect between Biden's message, the macroeconomic data, and the apparent widespread dissatisfaction among ordinary Americans, White House Press Secretary Karine Jean-Pierre acknowledged that many voters remain worried about economic insecurity.

"It's an incredibly complicated time," Jean-Pierre said, adding that the State of the Union will be an "important moment" in the battle to change Americans' views.

"I think (at) the State of the Union he'll have an opportunity to talk directly to the American people, not just Congress, to talk about what we have done," she added.

© Agence France-Presse