Don Perata has spent at least $594,000 in his attempt to become the next mayor of Oakland, thereby demolishing the city’s expenditure cap of $379,000, according to campaign finance reports filed today with the city clerk’s office. It was the first time that a mayoral candidate has ever gone over Oakland’s spending limit. Perata contends that he can exceed the cap because a Sacramento group with close ties to him has gone over the cap as well. That group, Coalition for a Safer California, which is run by a longtime Perata friend and is funded by the ex-senator’s best donors, reported last night that it had spent at least $137,000 trying to get him elected.