Gatecrashing Greens arrested

New York police said Ms Stein and Ms Honkala were charged with disorderly conduct when they tried to enter the debate site at Hofstra University.

The Greens then held an impromptu press conference in which Ms Stein called the debate a "mockery of democracy."

Later, inside the building, two multimillionaires debated their versions of the future of the country.

A fired-up President Barack Obama persistently attacked Republican challenger Mitt Romney, offering a striking contrast from his listless performance two weeks ago.

He blasted Mr Romney's economic plans as harmful to the middle class and accused him of flip-flopping on energy and gun control.

Mr Romney retorted that the middle class "has been crushed over the last four years," and 23 million were struggling to find work.

He noted that if the jobless who were no longer looking for work were counted, the unemployment rate would be 10.7 per cent.

Mr Romney also repeated a pledge to declare China a currency manipulator.

"We can compete with anyone in the world as long as the playing field is level," he said. "China's been cheating over the years."

Mr Obama retorted: "You're the last person who's going to get tough on China."

He charged that Mr Romney made money from companies that outsourced jobs to China while running private equity firm Bain Capital.