The electors of president and vice-president of the United States shall convene at the capital of the state on the first Tuesday after the second Wednesday in December after their election, at the hour of twelve o’clock at noon of that day. If there shall be any vacancy in the office of electors, occasioned by death, refusal to act, neglect to attend or other cause, the electors present shall immediately proceed to fill, by ballot and by a plurality of votes, such vacancy in the electoral college. When the electors shall appear, or the vacancies shall have been filled as above provided, the electors shall proceed to perform the duties required of such electors by the constitution and laws of the United States.