Remember Ralph Nader? He was the Green party candidate who did pretty well in the US presidential election of 2000. He got plenty of press attention and nearly 3 percent of the national vote. He also took valuable votes away from the Democrat candidate Al Gore, effectively handing the presidency to George W Bush. Well now he's back, after announcing he'll run as an independent in this year's election.
This won't go down too well with the two people vying to be the Democrats' candidate this time, Hillary Clinton and Barack Obama. They'll fear that, in a close election against the Republicans' John McCain, Nader could again do well enough to split the left-wing vote and put McCain into the White House.
They shouldn't have anything to worry about though. There's no way the Democrats will allow Nader to repeat his relative success of eight years ago. When he ran as an independent four years ago, Nader struggled to get enough signatures to get his name on ballot papers in many states, as the Democrats' army of lawyers took legal action to try to keep him out. He ended up with just 0.3 percent of the vote. Expect something similar in November.
The main reason preventing third party candidates doing well in US politics is a lack of money. They only become eligible for official funding when they get 5 percent of the vote, and they're unlikely to get anywhere near that without pots of cash. The only person to manage it in recent times is the eccentric billionaire Ross Perot, who dramatically split the right-wing vote in 1992 and 1996, allowing Bill Clinton easy victories (the Republicans could reasonably say that Nader's role in Gore's defeat was simply a case of 'what goes around comes around'). Unless New York mayor and billionaire Michael Bloomberg decides to enter, nothing like that will happen this time.