Mr. Musk’s involvement in politics and his financial support for the president’s campaign were once seen by investors as a benefit to Tesla, fueling a steep rise in company shares after the election last year. That association has now turned into a liability. Tesla shares are down 40 percent from their peak in December.

One of the best-known Tesla analysts laid out a plan for the electric and self-driving vehicle giant’s board to curb the firm’s controversial CEO Elon Musk, the latest evidence of Wall Street growing fed up with Musk’s non-Tesla actions, including an ugly spat with President Donald Trump.