Sen. Elizabeth Warren (D-Massachusetts) wrote a letter to President-elect Donald Trump on Monday to request clear and transparent conflict-of-interest rules that would bind Elon Musk, the world’s richest man, during his role as a top Trump adviser.

Progressive Senator Elizabeth Warren challenged Donald Trump to set ethics guardrails to control a “massive conflict of interest” posed by Elon Musk’s unofficial role in the president-elect’s transition and incoming administration.

The Democratic senator said the absence of an ethics agreement for Musk would amount to "an invitation for corruption on a scale not seen in our lifetimes."

Sen. Elizabeth Warren is pushing President-elect Donald Trump to outline and enforce ethics rules on Elon Musk, a key member of his transition team who has been tapped to lead a group scrutinizing the same federal agencies that regulate his companies.

Sen. Elizabeth Warren (D-Mass.) is expressing her concerns about apparent conflicts of interest posed by Elon Musk serving as a top adviser in the new administration and asking for President-elect Trump to explain what ethics standards will apply to the billionaire businessman.