President Barack Obama and Mitt Romney's bitter war of words has heated up as the pair battle for America's top job.

Mr Obama used a rally in Milwaukee, Wisconsin, to chide his Republican rival as Mr Romney mocked the President in a speech in San Diego, California.

"This country doesn't succeed when only a very few do well," Mr Obama told supporters to a cacophony of whoops and cheers. "We can't move forward if we've got leaders who write off half the nation, calling them a bunch of victims who will never take responsibility for their lives. I don't see a lot of victims here today. I see hard working Wisconsinites."

Some 2,000 miles away, Romney hit back telling his Californian crowd: "His slogan of course is forward. I think forewarned is a better slogan for him. I mean, we know where it heads.

"We've seen this before. We can see it here, we can see it in Europe. We have to get America working again. We know how to make America work again. He doesn't."

Both candidates are gearing up for the first debate set for October 3 in Denver, Colorado.