Standing Rules of the United States Senate, Rule XII

Voting procedure

Paragraph 1 states that when the yeas and nays (a recorded vote) are ordered, the names of Senators shall be called alphabetically. Each Senator shall declare his assent or dissent to the question without debate. No Senator shall be permitted to vote after the decision has been announced by the Presiding Officer unless excused by the Senate. A Senator may withdraw his or her vote only with sufficient reason and with unanimous consent. No motion to suspend this rule shall be in order. The Presiding Officer may not entertain any request to suspend it by unanimous consent.

Declining to vote

Paragraph 2 states that when a Senator's name is called on a vote and that Senator declines to vote, he shall be required to assign his or her reasons for refusal to vote. The Presiding Officer of the United States Senate shall assign the reasons and submit these as a question to the Senate. "Shall the Senator for the reasons assigned by him, be excused from voting?" This submission to the Senate is not debatable. A roll call and result of yeas or nays are followed by the normal proceedings of the Senate.

Conflict of interest

Paragraph 3 states a member may decline to vote in committee, on the Senate floor, or on any matter believes that his voting on such a matter would be a conflict of interest. This in spite of any other provisions of this rule.

Unanimous consent usage

Paragraph 4 states that a Senator may not request a unanimous consent in the taking of a final vote on a specified date upon the passage of a bill or joint resolution. It shall be submitted to the Senate for agreement after a quorum call is ordered for this purpose by the Presiding Officer and shall be determined that a quorum of the Senate is present. When a unanimous consent is given the same shall operate as the order of the Senate. Any unanimous consent may be revoked by another unanimous consent granted in the manner prescribed above upon one day's notice.