First, a little correction: The correct spelling is "consigliere", not "consigliore"
As Jespah says, it is
an Italian word, and it does
mean "counsellor" in Italian. Additionally, when used in English, consigliere
has the specific connotation of "counsellor to a Mafia boss". Are you familiar with the world of American movies and TV? Tom Hagen in The Godfather
and Silvio Dante in The Sopranos
are both consiglieri
By calling Baker a consigliere
rather than an adviser
, the author in fansy's example is hinting that the Bush family is something like a Mafia clan.