new book , clinton cash , points to ` pattern ' of donations and rewards .
says those who gave money to foundation saw favorable outcomes .
writer peter szhweizer points to dealings in colombia , haiti , kazakhstan .
revelations will be seized upon by republicans in white house race .
clinton allies have written of the book as an ` absurd conspiracy theory '
white house declined to categorically rule out any occurrence of wrong doing but said there 's no ` tangible evidence to indicate that it did '
president 's spokesman said he 's not going to be in a position ` every time somebody raises a spurious claim ' to ` say that it 's not true '