The US is really a two-turn voting system. The first turn is the primaries. It's quite different from the French presidential election, but the first round is

The US is really a two-turn voting system. The first turn is the primaries. It's quite different from the French presidential election, but the first round is open to all candidates. A non-aligned candidate would have to formally join a party to run for the nomination, but that's a matter of paperwork, not ideology. If they win office, they owe the party no obligations at all. The French system may well be preferable, but the American system really does have more opportunities for non-aligned candidates than people realize. They tend to dismiss the primaries as unimportant, but they really are a first round of voting -- that's why they're called "primary". Anybody who wants influence can start there, rather than jumping straight into the general election.