US Elcetions Explained

In US there are only two parties, namely Democratic and Republican. US presidential election occurs after every four years. In US Congress consist of two parts. House of Representatives and Senators. There are two senators from every state where as number of house of representatives will depend on population of particular state. Currently total senators are 100 and House of representatives are 435. And 3 members from Washington D.C. . So in total there are 538 members of House of Representatives.
Before more than 1 year of election both the parties will start searching for suitable candidate for presidential election. In US presidential candidate will also be chosen by people. For that in every state primary or caucus are organised. Primary or caucus are almost same as election. But they will be held by state government and one for each party. People who are loyal to particular party will participate in Primary/Caucus for that party. In primary people will caste there vote and based on majority, the candidate will be selected. In caucus people marketing for particular candidate will discuss about the candidates with other people in group. The candidate, whose group are smaller will have to merge into other groups. And finally there will be elections between two groups.