The Root of the Behavior
These imprinting behaviors are common, however, it is not necessarily the only cause of this needy behavior. A canine may maintain physical contact for other reasons. They may be trained to maintain contact from protection or attack style training, they may maintain physical contact because you often pet them or give them a bone to distract them when they become so aggressively needy, or they may try and maintain a direct physical contact because they suffer from a severe separation anxiety. Regardless of the cause of the cause of the behavior, it can become increasingly important to correct as the burden of their constant need for attention can impact your daily life or routine. Fortunately, there are things you can do to correct this behavior. Depending on what is causing it, these can either be pretty quick and easy fixes or something that may take some additional time and structure. If you cannot identify the cause of the behavior, it may be wise to contact a professional trainer or behavioral specialist.
Encouraging the Behavior
That being said, start with supplying your dog some fun things to do that do not require your assistance. Some dog toys and what not might do wonders. If they have something better to do then they may start to leave you alone more and more over time. As this happens, they will understand that they do not need you constantly and begin to detach themselves from you. A friend can also help with this issue. A neighbor dog or a new puppy in the house will give them a friend and a way to use their time other then sitting up against your leg the entire time you are home.