Ms. Masur took in $28,202, according to a campaign finance report for the last six months of 2011. Among her donors is supervisor and former sheriff Don Horsley, who contributed $500.
Candidate Guillermo "Memo" Morantes, a resident of Menlo Park and a member of the county Board of Education, reported total contributions of $37,329, but that includes a $25,000 loan to himself.
Ernesto "Ernie" Schmidt, a Redwood City planning commissioner, raised $9,935, and East Palo Alto Councilman David E. Woods, $495, according to the report filed with the county Elections Office.
No reports were provided for East Palo Alto Councilman Carlos Romero or Menlo Park Councilwoman Kirsten Keith. Ms. Keith announced Saturday that she was running.
A primary election is set for June, with a November runoff required if no candidate wins a majority. Ms. Jacobs Gibson, the current occupant of the seat, was appointed by the board in 1999, and elected in 2000, 2004 and 2008.