The phrase “how many seats flipped” typically refers to which political body and election cycle are in question. If you’re asking about the U.S. Senate flips in the 2024 elections, Republicans flipped four Democratic-held seats to gain a majority. If you meant a different body or a different year's elections, please specify the jurisdiction (e.g., U.S. Senate, state legislatures, or a particular state) and the election year, and I’ll provide the exact figure.
