debate as to whether the clause as written allows disqualification from the presidential position, or whether it would first require litigation outside of Congress, although there is precedent for use of this amendment outside of the original intended purpose of excluding Confederates from public office after the Civil War. Under the Twenty-second Amendment, no person can be elected president more than twice. The amendment also specifies that if any eligible person serves as president or acting president for more than two years of a term for which some other eligible person was elected president, the former can only be elected president once. Campaigns and nomination 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 presidential nominee. 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 presidents is lawyer. 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. Election The president is elected indirectly by the voters of each state and the District of Columbia through the Electoral College, a body of electors formed every four years for the sole purpose of electing the president and vice president to concurrent four-year terms. As prescribed by Article II, Section 1, Clause 2, each state is entitled to a number of electors equal to the size of its total delegation in both houses of Congress. Additionally, the Twenty-third Amendment provides that the District of Columbia is entitled to the number it would have if it were a state, but in no case more than that of the least populous state. Currently, all states and the District of Columbia select their electors based on a popular election. In all but two states, the party whose presidential–vice presidential ticket receives a plurality of popular votes in the state has its entire slate of elector nominees chosen as the state's electors. Maine and Nebraska deviate from