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The Primary
In states holding them, presidential primary elections are open to all registered voters. Just like in general elections, voting is done through a secret ballot. Voters may choose from among all registered candidates and write ins are counted. There are two types of primaries, closed and open. In a closed primary, voters may vote only in the primary of the political party in which they registered. For example, a voter who registered as a Republican can only vote in the Republican primary. In an open primary, registered voters can vote in the primary of either party, but are allowed to vote in only one primary. Most states hold closed primaries.
Primary elections also vary in what names appear on their ballots. Most states hold presidential preference primaries, in which the actual presidential candidates' names appear on the ballot. In other states, only the names of convention delegates appear on the ballot. Delegates may state their support for a candidate or declare themselves to be uncommitted.
In some states, delegates are bound, or "pledged" to vote for the primary winner in voting at the national convention. In other states some or all delegates are "unpledged," and free to vote for any candidate they wish at the convention.
The Caucus
Caucuses are simply meetings, open to all registered voters of the party, at which delegates to the party's national convention are selected. When the caucus begins, the voters in attendance divide themselves into groups according to the candidate they support. The undecided voters congregate into their own group and prepare to be "courted" by supporters of other candidates.
Voters in each group are then invited to give speeches supporting their candidate and trying to persuade others to join their group. At the end of the caucus, party organizers count the voters in each candidate's group and calculate how many delegates to the county convention each candidate has won.
As in the primaries, the caucus process can produce both pledged and unpledged convention delegates, depending on the party rules of the various states.
