Created by state voters in 2008, the 14-member California Citizens Redistricting Commission is tasked with revamping California's state and national districts with the latest census results instead of leaving the revamping up to lawmakers.
A congressional district must now have about 702,000 residents within it, and state law prohibits drawing district lines that significantly break up minority groups in a community.
If proposed districts introduced by the commission Tuesday are any indication, Rohrabacher's quest for a 13th term might not be a lock.
Leading up to a rough draft of the state's congressional districts set to be released Friday, the commission introduced a hypothetical map of what it is considering.
In the map, Huntington Beach and Costa Mesa are grouped with Irvine and Newport Beach.
Huntington Beach and Costa Mesa now belong to Rohrabacher's district and make up about half of his 46th Congressional District, which winds up to coastal Long Beach and Palos Verdes.
On the other side, Rep. John Campbell (R-Irvine) represents most of Newport Beach and half of Irvine, a bulk of his constituency.
By law, the citizens commission cannot assign representatives to the prospective districts, so neither Rohrabacher nor Campbell know if the Huntington Beach-to-Irvine district would be theirs.
Both showed strong support during the 2010 elections, each winning with more than 60% of the vote.
A second draft will follow in July and a final district map is expected in mid-August.