The slogan of US Democratic presidential candidate Barack Obama has always been "change we can believe in", but he recently quietly changed this well-known slogan to "change we need".
Since the end of August, Obama has adjusted his slogan and used the sign "We need to change" at the rally.
Obama wants to send a clear message to voters: only he can bring about the changes that America needs.
Obama said on 16: "This is the change that Americans need. Although McCain talks about change these days, his economic policy will only continue the old road. "