San Francisco Mayor Ed Lee announced Thursday that he's running for re-election. Four days later, his campaign already hit its first setback. Sen. Dianne Feinstein told the Chronicle that she's not ready to endorse him for a second term, citing concerns with local Airbnb laws. Maybe she's looking at the alternatives?

For much of Ed Lee's first term as Mayor of San Francisco, he enjoyed both the popular support of the public and the financial backing of tech tycoons. Last March, a stunning 65 percent of local voters approved of Lee's handling of the job. Then the Google Bus protests happened, the cost of living kept rising, and evictions hit crisis levels. Within 13 months, Lee's approval rating sunk by 20 points.