When is “Oversight” Really “Overkill”?

The U.S. Constitution gives the right to Congress to do “oversight” on the Executive Branch of government, but when doing that job, it should be for a legislative reason and not for vindictiveness, like what the Congress has being doing since President Trump took office. Should any sitting president, Republican or Democrat, be harassed continuously by an opposing party that wants him removed from office, for no valid reason other than that he won the office of president when he wasn't supposed to win? Not only has the president been harassed, but so has his immediate family, his cabinet members, and his office staff and political supporters. These vicious actions by his detractors are “overkill” and totally irrational. Is this what Congressional “oversight” is supposed to do?