If we look closely at the Constitution, we cannot hesitate. It is assumed by the Committee that there are but three qualifications for a Senator, and these words are quoted:—
“No person shall be a Senator who shall not have attained to the age of thirty years, and been nine years a citizen of the United States, and who shall not, when elected, be an inhabitant of that State for which he shall be chosen.”
According to these words, the three qualifications are (1) age, (2) citizenship, and (3) inhabitancy of the State he assumes to represent. These qualifications are not questioned, because they are grouped in a special clause of the Constitution; and every applicant, on presenting himself here, is subjected at once to these tests. But it is a mistake to suppose that these are the only qualifications imposed. There is another, mentioned in a later part of the Constitution, more important than either of the others; so that, though last in place, it is first in consequence. It is loyalty, which I affirm is made a qualification under the Constitution; and we have already seen, that, even if the organic law were silent, it is so essential to the fitness of a Senator for his trusts, that the Senate, in the exercise of its discretion, ought to require it. But the language of the Constitution leaves no room for doubt.
The words establishing loyalty as a qualification are as follows:—
“The Senators and Representatives before mentioned … shall be bound by oath or affirmation to support this Constitution.”[201]
These words are explicit in requiring the oath to support the Constitution. And the first statute of the First Congress, approved June 1, 1789, and standing at the head of our statute-book, provides for the administration of the oath as follows:—
“The oath or affirmation required by the sixth article of the Constitution of the United States shall be administered in the form following, to wit: ‘I, A. B., do solemnly swear, or affirm, (as the case may be,) that I will support the Constitution of the United States.’ …
“The President of the Senate for the time being shall also administer the said oath or affirmation to each Senator who shall hereafter be elected, previous to his taking his seat.”[202]