Answer: gwb

AnswerCrossword Clue
GWBPresident before BHO
GWBWJC follower
GWBNYC Hudson River crossing
GWBBHO's predecessor
GWBMonogram of the author of "A Charge to Keep: My Journey to the White House"
GWBWhite House monogram
GWBPres. after WJC
GWBPres. before Obama
GWB2001-09 U.S. pres.
GWBSuccessor to W.J.C.
GWB43rd prez
GWBPrez with the same initials as an N.Y.C. landmark
GWBEarly 2000s White House inits.