Trump is described as a one-off political figure who broke the American political system, a framing that unsettles both parties.

• The argument: Trump is a black swan — an event nobody planned for and nobody can repeat.
• Both parties built their playbooks for a kind of candidate that no longer exists.
• No successor is expected to inherit the same pull with voters.
• The system he strained is still running on rules written before him.

Outlook: Expect the fight over who inherits his coalition to shape the next election cycle.