ear to the ground

noun2

1. •
   The practice or characteristic of carefully gathering information; a state or mindset of attentiveness.

   • Congress never enacts a measure which is believed to oppose public opinion;—your Congressman keeps his ear to the ground. — 1903
2. •
   [before a noun] Pursuing the practice or having the characteristic of carefully gathering information; well-informed.

   • The ear-to-the-ground President knew that all the unrest could not be blamed on Communists. — 1949