(Portland, OR)  --  Police are searching for two suspects accused of cracking a man's skull while trying to rob him in northeast Portland.  Police say the man was walking to his car near Martin Luther King Jr. Boulevard and Northeast Schuyler Street just after midnight yesterday when two men approached him on bicycles.  Police say the men demanded money and then hit the victim over the head with either a hammer or a hatchet.  Anyone with information is urged to contact police.