Lee filed the "Statement of Organization: Recipient Committee" form 410 with the city's election department under the name "Barbara Lee for Oakland Mayor 2025" and named herself as treasurer.
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It's one of the first steps candidates are required to take before starting to raise money for their campaigns. Lee also filed a candidate intention statement.
Representatives for Lee weren't immediately available for comment.
So far, in addition to Lee, 13 people have filed papers signaling a potential run for Oakland mayor, according to a list posted on the city's website last Friday. The nomination period closes on Jan. 17.
The new mayor will be selected in the special April 15 election to replace ousted mayor Sheng Thao, who lost a recall election in November.