Incumbent Lois Capps, running for re-election in the 23rd Congressional District, could face opposition from a fellow Democrat, half a dozen Republicans and a Libertarian.
Capps, whose district encompasses Northern Santa Barbara County and much of San Luis Obispo County, has represented the area since 1998.
Republicans who have taken out papers to run against Capps include Carole Miller, Dave Stockdale, Albert Mercado, Clark Vandeventer, Thomas Watson and John Davidson.
George Mathy, a Ventura County Democrat, also has expressed his intent to challenge the incumbent.
Darrell Stafford, a Libertarian, also could be on the ballot.
All the would-be candidates still need to have their information checked and to be vetted by the Secretary of State’s Office, according to San Luis Obispo County Clerk-Recorder Julie Rodewald.
Rodewald said others may have filed on Friday, the deadline, and may not be recorded in the system yet.