US President Barack Obama has given his angriest speech since he was elected while a debate rages over his healthcare reforms. Mark Mardell considers whether America really is more divided than ever.
Protesters have declared war on Obama's healthcare policies
When the bearded activist in wraparound sunglasses put his hand on my shoulder, I felt his anger.
Not in an intuitive Californian sense - his jittering arm physically transmitted the motion of a body literally trembling with rage.
He was part of what is known as the Tea Party movement, the conservative opposition to Washington politics.
He had joined a demonstration outside a college in Philadelphia, where President Obama was about to give a speech on his plans for healthcare reform.
Taking his hand off my shoulder, the protester pointed to his placard. On it was a cartoon of the president as Batman's arch villain, the Joker, in white make-up with a creepy, clownish, slash of scarlet for a mouth.
He jabbed at one word on the banner: war. "That is what it means," he told me. "War. Civil war."
There is little doubt American politics is going through a torrid period but is it really nastier than before?
Every day I am told the frustration with Washington is greater, politics is more vicious, more partisan, America is more divided than ever.
The Washington Post writes of chaos, a political storm, disarray and disorder. And that is all in just one edition of the paper.
I was chatting with a veteran American cameraman who has covered every presidential election for 30 years.
He believes the poll in 2012 will be the nastiest yet.
Below the belt?
Certainly the case for the prosecution is strong and healthcare has its fingerprints over most of the exhibits.
One congressman has accused the president's chief of staff of being the son of the spawn of the devil.
The odd thing is, they are both Democrats.
Obama's health proposals would be too right-wing for Europe's conservatives
The congressman claims he was forced to resign, not because he made lascivious remarks to a male staff member after apparently drinking 15 gin and tonics and numerous bottles of champagne, but because he voted the wrong way on healthcare.
Healthcare is also central to a Powerpoint presentation by Republican fundraisers, which features the cartoon I have mentioned before.
Not only is the president depicted as the Joker, but the Speaker of the House Nancy Pelosi is shown as Cruella de Vil, and the Leader of the Senate Harry Reid is pictured as Scooby Doo.
The association with possibly the most irritating cartoon character ever does seem below the belt, and the Republican leadership has distanced itself from the planned campaign and its slogan: Save the country from trending toward socialism.
While it is clearly too late to stop the US trending toward using nouns as verbs, I can ask: "Is the US trending towards the nastiest set of elections ever?"
The sharp divisions between parties that are normal in British and European politics have been muddier here
But surely the political atmosphere now is not as sour as it was when I was a teenager, when you could feel the waves of hatred towards Nixon washing across the Atlantic.
Is it worse now than in the era of race riots and Vietnam protests, when students were shot dead on campus?
Is it worse than when congressmen shared cosy bipartisan drinks on the Hill, but Americans could not share the same drinking fountain? Hardly.
But perhaps this is the latest tremor in a decades-long seismic realignment of American politics.
It seems to me the sharp divisions between parties of left and right that are normal in British and European politics have been muddier here.
The broad coalitions often reached deep into each other's middle ground. A lot of it is to do with the legacy of their civil war.
The Democrats could never become a serious liberal or left-wing party while so many of their members from the South defended white supremacy.
The way forward in healthcare has bitterly divided Americans
Those days may be long gone but there are still social and fiscal conservatives who might be more comfortable as Republicans but are in fact Democrats, because, well, because Grandaddy was.
One British left-winger used to say: "There are two parties in American politics; one is like our Conservative Party. So is the other."
He had a point. But perhaps not any more.
The people on both sides who paraded their bitter divisions on the streets during the 60s and 70s have been steadily moving indoors, into the Senate, the Congress and the White House.
And America cannot really get used to the fact politics cannot be bipartisan while there is such an ideological gulf between people and parties.
At that Philly rally, I chat to several white-haired ladies who joke that my TV microphone looks just like their feather duster.
There are people in the US who would see David Cameron as a socialist
A retired couple, enjoying one of the first Spring-like days since the snow, placidly share their firm beliefs with me: Obama, they maintain, is a socialist and healthcare is about a government power grab.
This is where there is a cultural gulf. No Conservative party in Europe would touch Obama's proposals. They are far too right-wing.
And there are people in the US who would see David Cameron as a socialist, after all he supports a state-run national health service.
One version of the many Tea Party pledges I have seen has, as point seven: "I work hard for what I have and I will share it with who I want to. Government cannot force me to be charitable."
One of the refreshing things about American politics is that it questions what to us has become common place.
While they may argue about the detail, all British political parties support the redistribution of wealth through a progressive tax system.
Many in the Tea Party movement see that as creeping socialism. This is about what sort of country America becomes - and it is bound to get even angrier.
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