The US Constitution has rules on presidential terms. The 22nd Amendment says that no person can be president more than two times (eight years) in a lifetime. This means Donald Trump is not eligible for a third term as president if he wants to serve until his current four-year term ends.
Source: https://www.bloomberg.com/news/articles/2025-10-27/can-trump-serve-a-third-term-as-president-what-the-22nd-amendment-says