Where does the nomination happen for the republic and democratic party?

in the primary election.

Explanation:

During the primary election, the people can vote for the person who will represent the party in the general election.

Keep in mind that the winners of the primary election does not won the general election. They only won the right to become a candidate that will compete with another party.

The way a party run their primary election tend to varies. But in general, there are two types of primary election. Closed primary (where only the registered members of the party can cast a vote) and open primary (the all people can vote)

i believe that the answer to the question provided above is that the role of campaign committees is to act as a bridge between state and local campaigns.