As the United States approaches its 250th anniversary, a new Daily Mail poll reveals a nation deeply divided over its own greatness, with the political fault lines beneath America's patriotism never looking starker.

A new Daily Mail/JL Partners poll found that 68 percent of Americans believe their nation reigns supreme, but the figure masks a chasm between the parties: a thumping 91 percent of Republicans agree, compared with barely half of Democrats at 53 percent.

The optimism curdles when voters are asked about the future, with fewer than half, just 44 percent, convinced that America's best days lie ahead. Only 29 percent are willing to declare that its glory days are behind it.

Once again, it was Republican voters carrying the torch of hope, with 66 percent betting on brighter days to come, against 34 percent of Democrats.

Looking centuries ahead, 58 percent are confident the Stars and Stripes will still be flying in another 250 years, although fewer than half of Democrats, at 49 percent, share that faith.

Among the doom-mongers who fear the republic won't survive, economic collapse topped the list of nightmares at 22 percent, followed by nuclear war at 16 percent, civil war at 10 percent and, remarkably, a takeover by artificial intelligence at 9 percent.

Yet only 37 percent feel the country is on the rise, with 21 percent saying it is treading water, and a sobering 33 percent believe it is in outright decline.

The partisan gulf yawned widest here, with 64 percent of Republicans declaring America ascendant against a mere 23 percent of Democrats.

On the kitchen-table question of personal finances, the nation splits almost evenly three ways: 34 percent feel better off than four years ago, 29 percent about the same, and 33 percent worse off.

A clear majority, 58 percent, sense the country is hurtling toward a crisis, a fear shared by 76 percent of Democrats but just 37 percent of Republicans.

The uncertainty comes amid Donald Trump's confrontation with Iran, as well as tensions with NATO allies in Europe over the war in Ukraine.

Anxiety is mounting, too, with 47 percent more fearful about America's future than they were a year ago, while only 22 percent feel calmer and another 22 percent unchanged.

The poll was conducted between June 19-21 and surveyed 1,042 registered voters online, with a margin of error of 3.1 percent. 

Trump kicked off America's 250th birthday celebrations in Washington earlier this week, with stealth bomber and fighter jet flyovers and opera and classic American rock performances on the National Mall.

The 80-year-old President delivered remarks touting American prosperity while on the National Mall at the opening ceremony of the Great American State Fair on Wednesday evening.

Speaking from a stage in front of the Washington Monument, flanked by fair booths along the green lawn dubbed 'America's Front Yard,' where all 50 US states and six territories are represented, Trump promised a fiscal renaissance.

'We are beginning the most unforgettable birthday party any country has ever seen,' Trump declared.

'America's 250th year is set for an economic boom, the likes of which no nation has ever seen before,' Trump said, claiming gas prices would soon drop further because of his negotiations with Iran to end the war.

Past Daily Mail/JL Partners polls have shown that voters' top concerns heading into the November midterms are affordability, inflation, and the economy. 

Back on stage, Trump promised a slew of patriotic festivities that could take voters' minds away from the economy, ranging from a grand prix down DC's Pennsylvania Avenue to the largest fireworks show ever done for Independence Day.

'Today we have the largest economy on earth, we have the strongest military on earth, we have the most powerful technology on earth, we have the greatest culture on earth, and above all, we have the greatest people on earth,' Trump declared.