Tesla shares fell nearly 8% on Monday after CEO Elon Musk's plans to launch a new U.S. political party reignited concerns about his commitment to the company's future as it struggles with declining sales.

Elon Musk isn't done with politics just yet. Days after the SpaceX and Tesla CEO threatened to form his own political party as an alternative to America's "Democrat-Republican uniparty," Musk has announced his pledge to do so.

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.

The Tesla CEO says both parties have failed and claims The American Party will fight government bloat, attract disillusioned Democrats, and shake up the system.

Ross Gerber, a longtime Tesla investor and vocal Musk critic, didn’t hold back online, writing in his own post that, “no one wants the Elon first party,” accusing the company’s board of being “Elon vampires sucking the blood of Tesla equity.”