President Barack Obama announced his re-election bid on Monday with much the same tools that won him his first term in 2008, a mass-contact email to supporters and a video on the web ending in a slogan: It begins with us.
He is expected to file his papers later in the day.
His Republican challenger will emerge from among the five names in the ring: Mitt Romney, Mike Huckabee, Tim Pawlenty, Newt Gingrich and, the most closely watched, Sarah Palin.
First-term US presidents are automatically in the fray for their second and final term.
“We're doing this now (two years ahead of polling) because the politics we believe in does not start with expensive TV ads or extravaganzas,” Obama wrote in his email, "but with you — with people organizing block-by-block, talking to neighbours, co-workers, and friends."
“We'll start by doing something unprecedented: coordinating millions of one-on-one conversations between supporters across every single state, reconnecting old friends, inspiring new ones to join the cause.”
Political watchers expect Obama's campaign to raise $ 1 billion this time, compared to $ 750 million in 2008. The big collectors have been apparently asked to organise $ 250 million each.