A political party is a coalition of various groups.
A candidate tries to build a coalition of voters with a unifying simple message such as build a wall or no new taxes.
Trump won in 2016 by emphasizing a border wall (Mexico).
His emphasis this year should be inflation and immigration.
Most voters are single issue voters, i.e. one issue trumps all other issues
A candidate tries to build a coalition of voters with a unifying simple message such as build a wall or no new taxes.