London (CNN) The most unpredictable and consequential election this year isn't playing out in the town meetings of New Hampshire or the fields of Iowa. It's happening an ocean away, in the United Kingdom.

Politicians always say that the election they are fighting is the most important for a generation -- but in the UK, for once, that might just be true.

That's because British voters next week face choices that could reshape their country's global role for years to come.

They could put the ally that has a "special relationship" with America on a course that tears the UK apart by reviving dreams of Scottish independence. Or that rips the island nation out of the European Union with potentially damaging blows to the global economy. Or that causes the demise of Britain's nuclear arsenal, a pillar of NATO.

"We could see over the next five years Scotland going for a referendum for independence again. We could see a referendum on Britain's membership of the European Union, which might result in Britain leaving Europe," said Joe Twyman, head political and social research at YouGov, a British public opinion research firm.

"This could have enormous implications, both for people in this country now, but also for generations to come."

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UK unity in the balance

And there's more than the UK's future as a unified nation on the line. The country's entire political system is on the verge of a lurch into the unknown after decades of political stability that produced massive majorities for prime ministers such as Tony Blair and Margaret Thatcher.

The big established parties, Labour and the Conservatives, are seeing their authority fray in a volatile new era in which smaller parties based on regional and single-issue loyalties are likely to pack a much harder punch than their size would suggest. That's because they can play hard-to-get when they are wooed by bigger parties trying to frame a coalition.

Meanwhile, if Prime Minister David Cameron's Conservatives remain at the helm of government, the country will be on the path to a referendum on whether to stay in the European Union.

Cameron is promising to renegotiate the terms of Britain's membership in the bloc and to hold a vote by 2017 on whether Britain should stay in. The result of such a referendum is difficult to forecast. But the mere prospect of a British exit -- known as a " Brexit " -- could hammer the sickly European economy.

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Cameron's EU rethink came amid pressure from skeptical members of his own party and an insurgency from the United Kingdom Independence Party, led by charismatic everyman Nigel Farage, who wants to pull Britain out of the EU.

The party, which Cameron once derided as full of "fruitcakes, loonies and closet racists," threatens to siphon away votes from the Conservatives and make it much more difficult for the party to build a House of Commons majority.

But the real electricity of the race is in Scotland. Labour has traditionally been the dominant party for the working-class heartland north of the English border. But the Scottish National Party, despite losing a referendum on independence last year, looks set to wipe out Labour's support -- a scenario that would represent one of British politics' most staggering political realignments in decades.

The SNP surge might be coming at the expense of Labour — but given their common left wing-heritage, the two parties could find themselves thrown into a coalition together in Parliament. Such a tie-up would put the Scottish separatists in the unusual position of playing a major role in the government of a nation they have pledged to leave.

The rise of a popular Scottish politician

The resurgent SNP is being powered by a string of strong performances in debates and recent elections by Nicola Sturgeon, its new leader. Currently serving as First Minister of Scotland, Sturgeon is not even running for a seat in the UK parliament -- but polls show she is currently the most popular political leader in Britain. Both the Daily Mail and Sun tabloids have asked whether Sturgeon is the most dangerous woman in Britain.

In addition to seeking Scottish independence, the SNP is opposed to a project to update the UK's Trident nuclear missile system and may try to extract a promise from Labour to ditch plans for a new fleet of submarines to carry it.

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That has caused consternation in Washington over the kind of message standing down the nuclear arsenal would send about NATO's readiness and capability at a time when Russian President Vladimir Putin's revival of Cold War-style bombast has sent shivers through the West.

But while separatist fervor has taken Scotland by storm, apathy is a more accurate description of the electorate elsewhere -- despite the stakes in this election.

The polls have been stubbornly frozen for months, with Labour and the Conservatives neck-and-neck but both a long way from potential majorities. It seems public anger at politicians widely seen as on the take since an expenses scandal in 2009 has created an ugly inertia in which voters are loath to trust anybody.

This has lead to a situation where election day, May 7, may fail to produce a clear victory for any party but rather usher in a period of extreme instability. It might take days before Britons know whether their next prime minister is Cameron or Labour Party leader Ed Miliband.

The Liberal Democrats, the centrist party that has been in the coalition with the Conservatives for the last five years, meanwhile, is bracing for a tough night -- and may pay the price for serving in a government that has taken a tough austerity line.

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It's all a far cry from the days when Labour and the Conservatives took turns wielding power and elections were a two-horse race.

Potential post-election chaos is reflected in the political betting markets, legal in Britain, where gamblers often provide clues to the sentiment of a public expected to wager almost $40 million in this election season alone.

Graham Sharpe, a political expert and media relations director at William Hill, a major bookmaking firm, compared this year's chaotic election race to Britain's premier horse race, The Grand National, where favorites often fall at giant fences and outsiders can come from nowhere to make a stunning run for the front.

"It looks like a very competitive horse race. This time, anything can happen and not only do we not know what is going to happen — we don't know when it is going to happen."

Sharpe's firm reckons there are at least a dozen possible outcomes to the election, and that the Conservatives are most likely to win the most seats on May 7. But his oddsmakers think the most likely result of the election as a whole is a minority Labour government.

Fraying nerves as vote nears

It's clear the tight race election is beginning to fray the leaders' nerves. Cameron and the other candidates are throwing out proposals on everything from tax to home rent rules that already look impossible to honor.

On Tuesday, the Conservative leader rolled up his sleeves, took off his tie and told voters that he was ready to let rip in the final week of the election campaign.

"If I'm getting lively about it, it's because I feel bloody lively," Cameron said, trying to shake off his image as a man aloof from the suffering of everyday Britons -- an image that stems from his education in Eton, one of Britain's elite private schools.

On Monday, he kicked off his final push for victory by declaring in an interview with the Times newspaper that he had "only 10 days to save the union," arguing that Labour would enter a coalition with the SNP and trigger the biggest constitutional crisis since before World War II.

Miliband, the son of a famed socialist academic, has his own image problems. He has been lampooned for the clumsy way he ate a bacon sandwich and has had to struggle against the impression that he is just not quite prime ministerial material.

Earlier in the campaign, Miliband was asked whether he was tough enough to stand up to the likes of Putin. His reply, "Hell, yes, I'm tough enough," came across as staged and raised new questions about his authenticity.

But Miliband's populist anti-rich rhetoric, which mirrors the kind of denunciations of trickle-down economics uttered by U.S. President Barack Obama in his 2012 re-election campaign, touches a nerve in post-crisis Britain.

Miliband says that if the Conservatives win, the only people who will benefit are the wealthy. The campaign has also featured heated arguments on funding the state-run health care system and tough conditions hamstringing British workers.

But on one thing, at least, both men agree.

When he launched his campaign in March, Cameron said it was "the most important election in a generation."

Miliband said last week there were "10 days until the most important election in a generation ... 10 days until the tightest election in a generation."

Even the UK's skeptical voters may be able to take that much on trust from their beleaguered leaders.