Two of California’s best-known Democrats are slipping in the polls as the calendar advances closer to Election Day. In fact, both Lt. Gov. Gavin Newsom and U.S. Sen. Dianne Feinstein have only single-digit leads over their opponents, the results show. In the race for governor, a Probolsky Research poll, conducted between Aug. 29-Sept. 2, shows Newsom leading Republican businessman John Cox by a mere 5 points, with 17 percent of respondents undecided, the San Francisco Chronicle reported. Feinstein faces similar problems, with the poll showing her with only an 8-point advantage over progressive challenger Kevin de León. A quarter of...