Because they both belong to conservative Western astrological signs. That means that they fight in the same way, win for the same reason and loose for the same reason. Obama started out as a candidate for change. But he has adopted many traditional Democratic Party positions on many issues. So he may have lost support from some progressive Democrats, the same way Clinton has. Obama keeps fighting for the same votes as Clinton and so keeps losing the same votes that Clinton has lost. That is why he is having a hard time beating Clinton.