[2] Because he is not a member of the Senate. For this reason, also, he cannot take part in debates, nor can he appoint committees. These are elected by the Senate itself.
[3] But for his casting vote; a "dead-lock" might occur on some important question. This "might give rise to dangerous feuds, or intrigues, and create state or national agitations."
Clause 5.—Other Officers.
The Senate shall choose their other officers,[1] and also a president pro tempore,[2] in the absence of the vice-president, or when he shall exercise the office of president of the United States.
[1] These are similar to those of the House. (See p. 131.)
[2] The president pro tempore is chosen from among the senators. Being a senator, he can debate and vote upon any question. He cannot, of course, give a "casting vote," because that would virtually give him two votes.
The president pro tempore serves during the pleasure of the Senate, or until the expiration of his senatorial term.
It is the general practice for the vice-president to vacate his chair at the beginning of the session, to permit the Senate to chose a president pro tempore, so that if during vacation the vice-president should become president, the Senate might not be without a presiding officer. Until recently this was quite important, for the president pro tempore of the Senate was next to the vice-president in the succession to the presidency. But the succession has been changed. (See p. 190.)
Clause 6.—Impeachment.
The Senate shall have the sole power to try all impeachments.[1] When sitting for that purpose, they shall be on oath or affirmation.[2] When the president of the United States is tried, the chief Justice shall preside;[3] and no person shall be convicted without the concurrence of two-thirds of the members present.[4] Judgement in cases of impeachment shall not extend further than to removal from office, and disqualification to hold and enjoy any office of honor, trust or profit, under the United Sates;[5] but the party convicted shall, nevertheless, be liable and subject to indictment, trial, judgment and punishment, according to law.[6]