There shall be an Attorney for the State in each county and the City of Baltimore, to be styled "The State's Attorney", who shall be elected by the voters thereof, respectively, and shall hold his office for four years from the first Monday in January next ensuing his election, and until his successor shall be elected and qualified; and shall be re-eligible thereto, and be subject to removal therefrom, for incompetency, willful neglect of duty, or misdemeanor in office, on conviction in a Court of Law, or by a vote of two-thirds of the Senate, on the recommendation of the Attorney-General.