If a police officer is threatening me because I won't open my house for a search without a warrant, what do I need to do to stop this harassment?

I would go to the police department in question, and make out a report that the officer (hopefully you have his name) threatened to arrest you if you did not allow a search of your home. Tell them he also threatened to have you fired from your job. Tell them you are here to turn yourself in for the arrest. Of course, the officer was lying to you, as you do not have to permit the police to search your home without a warrant, except in "exigent circumstances." If there were any exigent circumstances, he would have pushed by you to enter the home without your consent. If the local police will not take your complaint, bring it to the State Police. The officer in question is breaking the law, and needs supervision by higher authorities, which will not happen without a citizen complaint.