A new poll commissioned by the Oakland Metropolitan Chamber of Commerce is showing a tight Oakland mayor’s race with a little more than six weeks to go until Election Day. Ex-state Senator Don Perata leads Councilwoman Jean Quan, 26 percent to 22 percent, with Councilwoman Rebecca Kaplan in third with 12 percent, said Scott Peterson, the chamber’s public policy director. Perata also has a slight lead when counting first and second choices under the new ranked choice voting system to be used in Oakland this year. He leads with 38 percent over Quan’s 34 percent. Kaplan, again, comes in third with 18 percent. The poll included 600 Oakland registered voters and has a 4 percent margin of error, meaning that Perata’s lead over Quan falls within that margin.