<Li> Under Section 3 of the Fourteenth Amendment, no person who swore an oath to support the Constitution, and later rebelled against the United States, can become president . However, this disqualification can be lifted by a two - thirds vote of each house of Congress . </Li> <P> The modern presidential campaign begins before the primary elections, which the two major political parties use to clear the field of candidates before their national nominating conventions, where the most successful candidate is made the party's nominee for president . Typically, the party's presidential candidate chooses a vice presidential nominee, and this choice is rubber - stamped by the convention . The most common previous profession of U.S. presidents is lawyer . </P> <P> Nominees participate in nationally televised debates, and while the debates are usually restricted to the Democratic and Republican nominees, third party candidates may be invited, such as Ross Perot in the 1992 debates . Nominees campaign across the country to explain their views, convince voters and solicit contributions . Much of the modern electoral process is concerned with winning swing states through frequent visits and mass media advertising drives . </P> <P> The president is elected indirectly . A number of electors, collectively known as the Electoral College, officially select the president . On Election Day, voters in each of the states and the District of Columbia cast ballots for these electors . Each state is allocated a number of electors, equal to the size of its delegation in both Houses of Congress combined . Generally, the ticket that wins the most votes in a state wins all of that state's electoral votes and thus has its slate of electors chosen to vote in the Electoral College . </P>

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