The candidates in the 1920 presidential election were Warren G.Harding and James M.Cox.

In reality, states have no position in the nomination of presidential candidates other than holding legal elections. The parties determine the candidates.

Yes; Mexico is a federal presidential representative republic, just like the United States.

Brian Dooley has written:

'Robert Kennedy' -- subject(s): Biography, Legislators, Politics and government, Presidential candidates, United States, United States. Congress. Senate

"Both major political parties in the United States select their presidential candidates through a process of primary elections. However, voters do not directly select presidential nominees in these primaries. Instead, they choose delegates from their respective states who will attend a national party convention to nominate a presidential candidate for their party." from thisnation.com