As a political anorak, I've always been fascinated by the American electoral system and, since I had to visit Los Angeles anyway, I thought I'd book my trip to coincide with the most important election in the world.

The battle for the White House was looking worryingly close and I decided that what the Democrats needed was my years of experience campaigning for the British Labour Party. With all my ideas and enthusiasm, I rolled up at a huge sound studio close to Hollywood, only to find they already had an election strategy of their own. With California judged as safe for the Democrats, activists here were focusing on contacting voters in swing states. "You will be phoning Wisconsin," said the woman leading my training session, "so no jokes about cheese." Everyone else laughed. I felt nervous calling a state where I didn't even know the comedy attributes.

Most of my years contacting voters in Britain have been via the old-fashioned method of knocking on doors. You waste an hour discovering that 30 people are not home. With telephone canvassing, it is far more efficient; in the same time, you can find 60 people who don't answer.

The script was quite strict. At no point was I allowed to scream, "You are voting for Mitt bloody Romney!? Are you completely mental? A president who believes that the Angel Moroni visited upstate New York with golden plates? And wouldn't Romney have just put the golden plates in an offshore tax haven anyway?" No, I had to read exactly what was printed on the sheet in front of me. "Hello [THEIR NAME], this is [YOUR NAME] …" Oh no, let's try that again. If they were voting Democrat, I told them where their polling station was and reminded them that the election was tomorrow. Not everyone knew this. Estimates are that each party spent about a billion dollars on this campaign, and still one bloke in Minnesota thought the election was the following Monday. I had wondered if my British accent might not be well received, but not a single voter raised it. They probably thought the Democrats were subcontracting their canvassing to call centres in the Third World, places such as Bangalore and England.

I will never get used to hoping that the electoral map turns blue. I thought it particularly galling that I'd travelled 5,000 miles only to see the first result of the campaign presented by Piers Morgan. For a while, it looked like we might be in for a repeat of the stalemate of 2000. "Can't we give Florida back to Spain?" suggested someone. Rumours of particular counties where they should have been doing better were worryingly relayed from laptops and iPhones, but gradually it became clear that Barack Obama would make it. There was particular delight that Fox News was the first to declare Obama the winner. And at the end of the night came a truly memorable victory speech from the re-elected President which spoke directly to everyone who had volunteered. He talked of the things that politics achieves and of the difference it makes to ordinary people's lives.

And that's when I realised that the best thing about American politics is people's very faith in it. They have more reason to be cynical about the system and yet Britain is the more cynical. US elections depend more on who raised the most money, yet they seem to attract more volunteers than we do. Americans still treasure the very notion of democracy, while we risk taking it for granted. So, if you were inspired by Obama's speech, don't just forget about it till next time. Get involved, like he said. Join the least imperfect party you can identify. Debate, engage and meet a lot of optimistic like-minded people, plus one bloke who's really boring about boundary changes. I don't think I changed a single voter's mind or got out a single extra Democrat. But I wouldn't have been anywhere else in the world. I was a tiny part of something that really mattered.

John O'Farrell's novel 'The Man Who Forgot His Wife' was published last month in paperback by Black Swan.