Sunny27-The functions of the political parties are to select candidates and raise money for the candidates representing the party.
The parties are responsible for fundraising and have many functions and parties to get large donors.
There is also a leader of the party and at the moment, Obama is in charge of the Democrat Party because traditionally the sitting president is in charge of his party and the other person is in charge of the Republican Party which is Michael Steele.
He also gives money to candidates to get them elected into office in order to further the Republican cause. The head of the party also campaigns for candidates all over the country. This is the main political party definition.