It is going to be very difficult to justify withholding a vote for Raphael Palmeiro when he becomes eligible for the Hall of Fame. Nevertheless, you may recall a few writers failed to vote for Willie Mays when he became eligible, so anything is possible when secret ballots are cast.
As of this writing Palmeiro has a lifetime batting average of .290, 534 home runs and 2874 hits. In his prime Palmeiro also fielded his position very well winning gold gloves in 1997 and 1998. Those numbers are Hall of Fame worthy by any standards.