SAN DIEGO >> The effort to recall San Diego’s embattled mayor is kicking off in the nation’s eighth-largest city today, one day before Bob Filner is set to return to work at City Hall after undergoing behavior therapy.

The petition drive to boot Filner from office amid sexual harassment allegations was free to officially begin at midnight Saturday, and organizers said they expected some volunteers to start gathering signatures right away.

"This is a tremendous grassroots undertaking — truly the people taking back their government from an abuser who has betrayed San Diegans, demeaned women and who can no longer lead our city," said Michael Pallamary, who filed the petition to recall the Democrat. "They’re ready to tell Filner, ‘It’s over, Bob. The people are going to show you the door.’"

The 70-year-old former congressman has resisted numerous calls to resign from the nine-member City Council, and state and federal elected officials, including House Minority Leader Nancy Pelosi, who has said that Filner should step down and spare San Diego the pain and expense of a recall election.

More than a dozen women have publicly accused Filner of making inappropriate statements or advances. The latest came Thursday when a volunteer city worker who assists senior citizens said Filner repeatedly rubbed her hands, asked her on dates and made sexually suggestive comments.

Recall organizers say they have raised more than $100,000 so far and more than 800 people have signed up to volunteer for the effort. A table will be set up Sunday at the finish line of "America’s Finest City Half Marathon" in Balboa Park, while businesswomen and military sexual assault victims will lead an afternoon "Freedom from Filner" march downtown. They also set up a website at http://www.RecallBobFilner.com , which includes a real-time mapping function for petition drive locations and petition forms to download and circulate.

The petitions will include Filner’s response, filed Monday with the city clerk’s office, in which he tells voters this is "not the time to go backwards" and touts his administration’s job-producing projects and quality of life initiatives, like removing cars from Balboa park and proposing the 2024 Olympic Games be held in San Diego and Tijuana.

Filner made no mention of the allegations against him in his response. He has said in the past that he has disrespected women but has denied being guilty of sexual harassment.

The recall effort must collect 101,597 signatures of registered San Diego voters by Sept. 26. If the petition has fewer than that, the recall campaign will have 30 more days to circulate a supplemental petition to gather the additional valid signatures.

If enough signatures are validated by the city clerk, the petition will be presented to the City Council, which must schedule an election within 60 to 90 days from then.

Filner’s lawyers said he completed two weeks of intensive behavior therapy. He is expected to return to work Monday.