be sitting in the catbird seat

be (sitting) in the catbird seat

To be in a powerful position. The phrase likely refers to the catbird's preference for high tree branches (which keep predators at bay). As the CEO's assistant, you are definitely sitting in the catbird seat. The retirement of the company's president left its vice president suddenly in the catbird seat.
See also: catbird, seat
Farlex Dictionary of Idioms.

be sitting in the catbird seat

or

be in the catbird seat

AMERICAN, OLD-FASHIONED
If you are sitting in the catbird seat or are in the catbird seat, you are in an important or powerful position. He'd go broke tomorrow if I left him, and I'd be sitting in the catbird seat. If the campaign is quick, short and successful, both leaders will be in the catbird seat. Note: This expression became widely known in the 1940s and 1950s, when it was used by the baseball commentator Red Barber. Catbirds are North American songbirds. The expression may be explained by the fact that catbirds often sit very high up in trees.
See also: catbird, seat, sitting
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • be (sitting) in the catbird seat
  • be in the catbird seat
  • catbird
  • catbird seat
  • the catbird seat
  • in the catbird seat
  • (sitting) in the catbird seat
  • catbird seat, (sitting) in the
  • get (one's) ear
  • deserting/leaving a sinking ship