SAN DIEGO -
A lot of money is being thrown into the San Diego mayoral election.
According to the city clerk, Councilman Carl Demaio raised nearly $648,000 the first three weeks of October for a total campaign coffer of $3.3 million.
His opponent, Rep. Bob Filner, D-San Diego, added $132,000 this month to his war chest of $910,000.
Campaign disclosures also reveal most of Demaio's outside backing comes from local businesses, while Filner's comes from local unions.
Both sides and their supporters have spent more than $10 million, making this the most expensive mayoral race in San Diego history.