CNN : Obama says he will file papers soon . NEW : Obama : We need to mobilize ` ` long before '' the time to seriously campaign . He is making his formal announcement slightly earlier than is typical for an incumbent . So far no Republican contenders have formally announced .
NEW : Obama says he will file papers Monday . NEW : Obama : We need to mobilize `` long before '' the time to seriously campaign . He is making his campaign official slightly earlier than is typical for an incumbent . So far no Republican contenders have formally announced .