In the first one she means that Obama is the obstacle she has to get past in order to be elected. By using a skunk, she's also insulting him as being someone distasteful and implying she doesn't want to be associated with him. In the US. Skunks are frequently run over by cars and their scent is released. It's a good idea to go around them or your car will smell bad too. In the second one she's just comparing him to something disgusting and implying that he has damaged the Democrats, making it more difficult for her, another Democrat to be elected.