<P> The Twenty - second Amendment to the Constitution states that an individual cannot be elected to the presidency more than twice . This prohibits former Presidents Bill Clinton, George W. Bush, and Barack Obama from serving as president again . Former presidents Jimmy Carter and George H.W. Bush, both having only served one term, are not constitutionally prohibited from being re-elected in the 2020 election . </P> <P> The age group of what will then be people in the 18 to 45 - year - old bracket is expected to represent just under 40 percent of the United States' eligible voters in 2020 . It is expected that more than 30 percent of eligible American voters will be nonwhite . </P> <P> The presidential election will occur at the same time as elections to the Senate and the House of Representatives . Several states will also hold state gubernatorial and state legislative elections . Following the election, the United States House will redistribute the seats among the 50 states based on the results of the 2020 United States Census, and the states will conduct a redistricting of Congressional and state legislative districts . In most states, the governor and the state legislature conduct the redistricting (although some states have redistricting commissions), and often a party that wins a presidential election experiences a coattail effect that also helps other candidates of that party win election . Therefore, the party that wins the 2020 presidential election could also win a significant advantage in the drawing of new Congressional and state legislative districts that would stay in effect until the 2032 elections . </P> <P> An incumbent president seeking re-election usually faces no significant opposition during their respective party's primaries, especially if they are still popular . For Presidents Ronald Reagan, Bill Clinton, George W. Bush and Barack Obama, for example, their respective paths to nomination became uneventful and the races become merely pro forma; all four then went on to win a second presidential term . Serious challenges are rare, but then generally presage failure to win the general election in the fall . During the 1976 Republican Party primaries, then - former California Governor Reagan carried 23 states while running against incumbent President Gerald Ford; Ford then went on to lose the presidential election to Jimmy Carter, albeit carrying more states . Senator Ted Kennedy then carried 12 states while running against Carter during the 1980 Democratic Party primaries; Reagan then defeated Carter in the fall of 1980 . Pat Buchanan captured a decent percentage of a protest vote against George H.W. Bush during the 1992 Republican primaries, but only received a handful of delegates; Bush too subsequently went on to lose in the general election to Clinton . </P>

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