Page "Twelfth Amendment to the United States Constitution" Paragraph 12

The Senate chooses the Vice President if no candidate receives a majority of electoral votes.

Its choice is limited to those with the " two highest numbers " of electoral votes.

If multiple individuals are tied for second place, the Senate may consider all of them, in addition to the individual with the greatest number of votes.

The Twelfth Amendment introduced a quorum requirement of two-thirds for the conduct of balloting.

Furthermore, the Twelfth Amendment provides that the votes of " a majority of the whole number " of Senators are required to arrive at a choice.