The Core Faction was one of the two major factions of senators and representatives in the Galactic Senate during the last years of the Galactic Republic. Most were Human, and astrographically most came from the Core Worlds. They were politically liberal, and so advocated increasing, or at least maintaining, the authority and powers of the Republic government. For at least the last few years of his service in the Senate, Bail Antilles was their leader.
Antilles' failure in the election was believed to be the reason he resigned from the Senate. His successor as faction leader was unknown, but they became Palpatine's prime seat of power, becoming the Senate's central power during the Separatist Crisis, Clone Wars, and Imperial Senate.
The Core Faction was opposed by the Rim Faction.