A push to challenge California’s new electoral map that deeply divided the Golden State’s Republican delegation appears to have lost momentum, leaving veteran GOP lawmakers such as Rules Chairman David Dreier with few options outside of running in unfamiliar or Democratic-friendly territory.

“My understanding is that there is not a signature gathering,” said Rep. Darrell Issa, referring to one option to challenge California’s new map: a referendum to put the new district lines, which could jeopardize as many as six of the 19 current state Republican Members, before voters.

Issa’s view echoed the accounts of several other California lawmakers. But Dreier, whose current district was dismantled by an independent commission, said, “I don’t know this to be the case” in response to questions about whether the effort is indeed dead.

For Dreier, the voter registration of his new district is nearly 24 points more Democratic than his current swing district, giving Democrats a 19-point advantage.

Reps. Elton Gallegly, Jeff Denham, Brian Bilbray and Dan Lungren also found themselves in districts with lower GOP registration numbers.

Republican Reps. Ed Royce and Gary Miller now share a district, making it likely the two will face each other in a primary if neither runs in a new district.

Dreier and the others do have an option to file a lawsuit against the new lines. But insiders say the effort would likely be doomed, because the legal standard for challenging the lines is tough to meet.

There are also rumors of Members maneuvering on which districts they’re running in.

“We’re looking forward to the process,” Dreier said.

A key question remains unanswered, which is who is behind a move to challenge the lines before voters.

Julie Vandermost, a political activist and consultant in Orange County, filed paperwork with the California secretary of state and attorney general on Aug. 30 to pursue the referendum to challenge the new Congressional lines.

To get the referendum before voters, Vandermost would need to file more than 500,000 signatures by Nov. 15.

Members of the California GOP Congressional delegation have denied they’re behind the push.

“Nobody’s really raising their hand, so if you can find that out, let me know,” one lawmaker said. “Everybody’s denying that they’re the one doing it.”

Vandermost, who lives in GOP Rep. John Campbell’s district, won’t say.

Campbell, who is opposed to the referendum push, said he called Vandermost, and she declined to say who was behind the effort. Vandermost did not return a phone call from Roll Call.

Dreier denied being behind the effort. “I’m not driving it,” he said.