National Security Adviser John Bolton has earned the nickname “President Bolton” among his critics for shrinking the number of people who are looped in on key policy discussions and fervently enacting President Trump’s “America first” agenda in national security matters, the Wall Street Journal reported.

Bolton has received criticism for his cunning ability to help shape Trump’s agenda interests in a way that aligns with his own personal crusades, like axing U.S. participation in the International Criminal Court, a topic that was not on Trump’s radar until Bolton joined the administration.

And people close to Bolton told the WSJ that the national security adviser must tread lightly if he wants to remain in the good grace of Trump, a president who has made it clear he doesn’t like to share the spotlight.

“If John ever behaved in a way that led people in the administration to refer to him as ‘President Bolton,’ his effectiveness would be destroyed,” longtime Bolton friend and former member of President George W. Bush’s National Security Council Elliott Abrams told the WSJ. “It’s critical that the President never think that, and no one understands that better than John.”