You can, it usually just makes you a pariah in your own party and I don't know if a primary challenger has ever won against an incumbent president. But there was a Republican primary this year, for instance; the incumbent doesn't just automatically get the nomination.
You can, it usually just makes you a pariah in your own party and I don't know if a primary challenger has ever won against an incumbent president. But there was a Republican primary this year, for instance; the incumbent doesn't just automatically get the nomination.