Elon Musk is testing the limits of legal and ethical restrictions on the role of special advisers in U.S. presidential administrations, according to some legal experts and lawmakers who oppose the billionaire's mission against what he deems wasteful government spending.

The billionaire has used the social media site to boast of victories, lash out at enemies and conduct polls for the initiative he calls the Department of Government Efficiency.

Elon Musk and his allies are harnessing tech units and other agencies that handle daily federal operations to amass sweeping control of the executive branch.

Tesla CEO, SpaceX founder and the richest billionaire in the world Elon Musk is now a U.S. government employee. What to know about his citizenship.

The SGE designation, which has come under scrutiny under Democrats as well, exempts short-term federal employees from certain disclosure rules.

Trump efficiency czar Elon Musk is taking drastic steps to tame bloated government. Critics say the Constitution is being shredded in the process.

Musk, who has promised "mass head-count reductions" across the federal bureaucracy, has drawn wide scrutiny in recent days as his team has been given access to or has taken contro