Critics of Sonoma County Supervisor Efren Carrillo are vowing to press forward with a recall attempt to oust him from office, although for now it's still mostly talk.

"The momentum continues to build. It's not going away," said Alice Chan, a Sebastopol-based Democratic Party activist and co-chair of the Coalition for Grassroots Progress.

The group had given Carrillo, who has been under fire since his July 13 arrest on suspicion of prowling and burglary, until last Sunday to resign his post or face a recall. Chan issued a statement Thursday announcing the group's intent to proceed, though she provided few details.

The cost to hold a special election in the 5th Supervisorial District for the purposes of a recall vote is estimated to cost $127,678 to $229,820, according to county election officials.

It also could be consolidated with another election, depending on the timing.

Chan said her group has not filed paperwork with the county election's office that is required before the group can begin the process of gathering signatures.

She couldn't say when the coalition might take that step. "I can't be pinned down to a date," she said.

Jack Buckhorn, president of the North Bay Labor Council, a coalition that could provide financial and political backing for a recall, said Thursday the group has not decided whether to back such an effort. The labor council has urged Carrillo to resign.

Recall proponents would have 160 days to gather signatures from the date county election officials determined the initiative met the requirements.

Proponents would need 7,661 signatures — 15 percent of the 51,071 registered voters who live in the 5th district — to qualify for an election. Assuming that happened, voters would have the choice of keeping Carrillo in office or voting for another person to replace him.

Carrillo handily won re-election in November. His term runs through January 2017.

Carrillo's July 13 arrest came after a pair of 911 calls from a woman in his west Santa Rosa neighborhood reporting that a man — later identified as the 32-year-old Carrillo, according to police — had tried to break into her home through a bedroom window.

Police, who arrested Carrillo in just his underwear and socks, have said the incident — which resulted in a torn screen on the woman's bedroom window — had the marks of an attempt at some type of sexual assault.

Carrillo, who is expected to learn Oct. 11 whether prosecutors will file charges against him, has said that he will not step down.