B
The power of the executive branch is vested in the President of the United States.As the chief executive of the nation，the President’s duty is to“preserve，protect and defend the Constitution of the United States”and to faithfully execute laws passed by Congress.
The Constitution delegated broad powers to the President.He has the power to issue rules，regulations and instruction（known as“executive orders”）to federal government agencies，to recommend measures for Congress to consider，to appoint important government officials and federal judges with the consent of the Senate，and to dismiss any federal official if he finds it necessary to do so.He can also pardon anyone who has been convicted of violating federal laws，but he cannot pardon himself or other federal officials in case of Congressional impeachment.As the Commander⁃in⁃Chief，the President has the power to raise，train，supervise and deploy American armed forces.As Head of State，the President has the power to conclude treaties with foreign countries with the consent of the Senate.
The President is assisted by a Cabinet in the execution of his duty.The Cabinet includes the Vice President and the heads of the executive departments，including the Secretaries of Agriculture，Commerce，Defense，Education，Energy，Health and Human Services，Homeland Security，Housing and Urban Development，Interior，Labor，State，Transportation，Treasury，Veterans Affairs and the Attorney General.The Cabinet members advise the President on important issues relating to the affairs of their respective departments.
Other important parts of the executive branch include the White House offices and agencies such as the National Security Council，the Council of Economic Advisors，the National Economic Council，and so on.The heads of these offices and agencies help to develop and in some cases implement the President’s policies and programs.
The President of the United States is elected for a term of four years by the Electoral College，whose votes are in turn determined by the results of the popular presidential vote.The number of electors in the Electoral College is the same as the total number of members in Congress，but no senators，representatives，or people who hold important federal offices can be electors.Each state sends a number of electors to the College equal to the total number of senators and representatives they send to Congress.The Presidential candidate who receives the majority of Electoral College votes becomes the President.Although the system is often considered outdated and undemocratic，it is still the way the U.S.President is elected today.The presidential election，as with most elections in the United States，is usually a contest between the two major parties：the Republican Party（with an elephant as its symbol）and the Democratic Party（with a donkey as its symbol）.While third parties participate in elections，they have never won the presidency.
The presidential election takes place in four main stages.First，each of the major parties conducts primary elections（also called“primaries”）in every state.Primary elections are held during the winter and spring of the year leading up to the main presidential election，and are contested among those politicians in each party who want to become President.The candidate who wins the popular vote in a primary election obtains the support of all or most of that states’delegates to the party’s convention.
The second stage of the presidential election process is the party conventions，at which the delegates from all the states vote to choose the Party’s presidential nominee.The Democratic and Republican conventions are held during the summer before the presidential election，and are also the occasion when each party officially adopts its election platform，which outlines the major policies it aims to adopt if victorious.
The third stage is the general election campaign，which takes place during the late summer and autumn of the presidential election year.At this stage，both parties and their nominees campaign vigorously.Each party runs advertisements that promote its own candidates and attack the candidates of the other party.Meanwhile，the candidates for President and Vice President travel around the country giving speeches，and also hold several televised debates.
U.S.Capitol，Washington，D.C.
The fourth stage is the general election，which is usually held in early November.The general election is counted separately in each state to decide which party’s presidential candidate will win the state’s votes in the Electoral College，which is the institution that elects president and vice president in the United States.Here，the rule is generally“winner take all，”which means that the candidate who receives the most popular votes in a state wins all that state’s Electoral College votes for that state.For this reason，both parties attach great importance to winning states with the largest numbers of Electoral College votes，such as California，Texas，and New York.Besides，the parties are also focused on swing states.
The total number of Electoral College votes is 538，so candidate has to obtain 270 Electoral College votes in order to win the election and become President.Because of the Electoral College system，sometimes a candidate can win more popular votes but still lose the election.For example，in the 2000 president election，Al Gore won many more popular votes than George W.Bush，but he lost the election because Bush got more Electoral College votes than Gore.This was due to Gore winning some states by large numbers of votes but losing many others by smaller numbers of votes.It is usually clear who the winner is once the general election is over.However，the result only becomes official when the Electoral College votes are formally cast over one month later，which technically is a fifth stage of the election process.
Presidential elections are very costly.Campaign funds generally come from two types of sources：private donations and government funds.If a candidate agrees to receive government funds during the general election，then there is a limit on the total amount that candidate can spend on their campaign.If the candidate decides not to accept government funds，however，then he or she can spend an unlimited amount.Small third parties receive funds from the federal government according to how many votes they received in the previous election，so they usually lack campaign funds and thus have little chance of success.
After the election，the winning candidate becomes the President upon being inaugurated into office on the following January 20.In November 2008，Barack Obama was elected as the first black president in the history of the United States.However，Americans have so far not elected a female president or vice president yet.