The Donkey represents the Democratic party – it is the symbol of the Democratic party.
The alarm clock represents the wake-up call that the attacks of 9/11 were to America (that there are Islamic extremists in the world whose goal is to destroy America).
Similar to a person who doesn’t want to react to his alarm clock (to get up and get moving), the cartoonist is saying that the Democrat party is choosing to ignore the warning of the 9/11 attacks and not take action, but turn over and go to sleep (the way America was before 9/11).