Obama and Romney: A battle of ideologies
It's not just the occupant of the White House that is at stake in the impending US election. Many believe the country is at a fork in the road, with two very different paths ahead of it.
When Americans cast their votes next month, it's probably not exaggerating to say they'll do so in the midst of a profound ideological divide.
"Clash of ideas."
"Two entirely different visions."
You hear it all the time. Not least from the candidates and their supporters. But where does this clash come from?
Try starting at the sprawling headquarters of the Social Security Administration, just outside Baltimore.
The organisation was established by President Franklin Roosevelt in 1935 as part of his response to the Great Depression.
It also ushered in an era of big government. The SSA now employs more than 60,000 people and in 2010 accounted for almost 40% of all government spending. It administers programmes - for the sick, the elderly and the poor - that are plunging the US deeper and deeper into debt.
Eighty years on, it's the size and role of government that represents the faultline between Barack Obama and Mitt Romney, who has vowed to bring government spending down to 20% of GDP by 2016, down from its current level of 24%.
Ron Brownstein, editorial director of the National Journal magazine, says Mr Romney is offering a surprisingly radical solution.
"If you go up and down what he's talking about doing, he is looking at an agenda that aims to dramatically undo the role of government in national life."
One of Mitt Romney's biographers suggests his family history informs this impulse.
"There's no question that he values the stories of his ancestors," says Michael Kranish, co-author of The Real Romney.
As Mormons practising polygamy in the late 19th Century, in defiance of federal law, Mr Romney's ancestors were forced to move to Mexico, only to return to the US following a revolution 27 years later.
"The family had to constantly rebuild itself when they were fleeing federal marshals," Kranish says. "He's absorbed some of these beliefs and it's part of the Romney family vision."
For presidential historian and former Republican speechwriter Richard Norton Smith, it also taps into an heroic version of American history.
"It accepts the heroism of the entrepreneur, the lonely man or woman with an idea and the force of character to pursue that against all odds, often in the face of a hostile government," he says. "Call it a myth, but myths take on a reality of their own."
Myths, of course, require mythical figures, and the Republicans have no problem coming up with one.
The shadow of Ronald Reagan still looms large over the Republican party.
It was, of course, Reagan who famously declared that "government is not the solution to our problems; government is the problem", as he assumed office in 1981.
Mitt Romney doesn't quite cast himself as a modern day incarnation. He may occasionally talk, as he did in New Hampshire last December, about the "invisible boot of government", but he only mentioned Reagan once during his speech at the Republican convention, and then only in the context of foreign policy.
In fact, in 1990s, Mr Romney used to describe himself as an "independent".
But in recent years, the Republican party has undergone a profound and rapid transformation, lurching to the right under the conservative Tea Party movement, with its uncompromising stance on fiscal responsibility and its open hostility to big government.
With the two main parties sliding further and further apart, Mr Romney has had to move with the times.
"Over the last four years, most Republicans and conservatives have looked at the Obama administration and thought there is no limitation any more to what Democrats will do to expand the role of government," says Vin Weber, a former congressman and now a Romney advisor.
"There has been a reaction in the Republican party to say we have to take a much firmer ideological stand. We have to stand up to everything."
During the Republican primary season earlier this year, he claimed to have been "a severely conservative governor". Most Republicans raised their eyebrows.
But what of Mr Romney's opponent?
When it comes to Barack Obama, we do at least have his record in office as a guide to the vision. But the president has been on quite a journey too.
When he took office, in the midst of the deepest crisis since the depression, some wondered if they were looking at the next incarnation of Franklin Delano Roosevelt.
The $800bn stimulus plan, enacted in the first month of Mr Obama's presidency, seemed to herald a similar approach.
But the president's opponents were quick to mobilise. Republicans denounced the stimulus plan and Mr Obama's proposed healthcare and financial reforms. The Tea Party noisily declared that enough was enough.
Stimulus became a dirty word and comparisons with FDR increasingly irrelevant. Eventually Barack Obama turned for inspiration to a different Roosevelt, Franklin's fifth cousin, Theodore. A Republican.
In 1910, Teddy was frustrated with the conservative wing of his own party. He gave a speech in Osawatomie, Kansas, in which he embraced the idea that only a powerful federal government could ensure social justice. He called it a new nationalism.
A hundred and one years later, Barack Obama travelled to the same Kansas town, to claim the vision as his own.
"Now, just as there was in Teddy Roosevelt's time," Mr Obama told his audience, "there is a certain crowd in Washington who, for the last few decades, have said, let's respond to this economic challenge with the same old tune. "The market will take care of everything."
It was a significant moment: a 21st Century Democrat, channelling the words of a 20th Century Republican in an effort to convince Americans in the conservative heartland that government isn't all bad.
But Barack Obama might just as well have been whistling in the Kansas wind. The gulf between America's two main political parties is simply too deep.
"We're in a period of great tension in this country," says historian Robert Dallek. "The Republican party has moved so distinctly to the right. The notion of consensus has been so pushed into the background."
The president who promised to rise above partisan politics found himself sucked into it instead. Amid the endless trench warfare of Washington politics, a weary, less transformational figure has slowly emerged.
A few months ago, Mr Obama admitted he was partly to blame, telling the CBS network that he'd failed "to tell a story to the American people that gives them a sense of unity and purpose and optimism".
For a serving politician, seeking re-election, it was an unusually candid confession. Particularly for a man who seemed like a natural communicator before he took office and who has regularly discussed the secrets of presidential success at White House dinners with historians like Mr Dallek.
"The most successful presidents have not only announced a vision," Mr Dallek says, "but described it in a concise way. Theodore Roosevelt talked about a square deal, FDR a new deal, Harry Truman a fair deal, Lyndon Johnson the great society, John Kennedy the new frontier and Ronald Reagan the Reagan revolution. This means something to people."
Barack Obama and Mitt Romney have both had problems with communication. Cool, analytical and instinctively centrist, they've sometimes struggled to make themselves heard above an uncivil, partisan din.
Their visions owe much to the growing divide, as the tectonic plates of American politics shift beneath their feet.
As historian Richard Norton Smith says, as they battle for office, each man is trying to tap into an authentic, but very different, idea of what it means to be an American.
"Although you wouldn't guess it, hidden inside the fog of political war, there is in fact a debate going on about the nature of the American character."
Listen to the two-part series, Two Men, Two Visions broadcast by the BBC World Service.