Sometimes these combine. Like, if the state wants to build a new road, they'll give the contract to whoever is going to donate the most to the governor's campaign during the next election, even if that means it costs a lot more.
It doesn't help that our voting system creates a scenario that will always devolve into just two political parties. Any third party candidate ends up being a spoiler for a similar party and guarantees a victory for the other major party. This is why Democrats are hoping Trump runs for President as a third party, as it would split the Republican vote and hand the Democrats an effortless win.
We only have direct democracy for local and state offices. Presidential elections are not a direct democracy.