...more than four democrats running in the primary can mean a lost seat by the GOP if they run just two republicans. We have a "jungle" primary where the top two vote-getters compete in November. No "Dem" against "Rep", just top two.
This was originally set up for third parties to split the Democratic vote, but it hasn't worked too well for the GOP - yet.
For example: In some seats, the Democratic winner ran against a fellow democrat because there were five or six GOP candidates running for the seat; not of the GOP candidates - running the gamut from Hyper-Evangelical to Chamber of Commerce to Libertarian, could win enough votes to beat either of the Democratic candidates.

What DWS is concerned about is several districts that have developed into generally blue - such as Issa's district - where there are up to 8 democrats running and none are willing to drop out to ensure the that there's a Democrat to run against one of the 3 Republicans running because they think they have the better ideology to run as a Democrat at the higher Federal level, instead of working their way through the Democratic party ranks beginning at the local and state levels.

We can really use some of those Democrats to really do some Good and run for County Supervisor or other County or State position instead of splitting the Dem vote for a US HoR seat.

San Diego County is blue in the cities and red rural, but as there's a crapload of rural in the County, they get to vote for the five County supervisors, and those five are as Prosperity Gospel/tea-party/CoC Red as any politician in Fresno or Bakersfield.
Seriously. Run for f'n County Board of Supervisor! Run for State Legislature! Run for School Board!
That's the way progressivism moves forward. That's the way to beat the frightened of reality troglodytes that took over the GOP.

Haele