When voting on judicial nominees, the Senate takes into account several factors, including:
1. Qualifications: The Senate considers the nominee's education, experience, and legal background, as well as their temperament, ethics, and overall fitness to serve as a federal judge.
2. Ideology: The Senate considers the nominee's political and judicial philosophy, as well as their views on controversial issues such as abortion, gun control, and civil rights.
3. Partisan politics: The Senate considers the nominee's political affiliation and how their confirmation might affect the balance of power on the Supreme Court.
4. Public opinion: The Senate considers how the nominee is perceived by the public and how their confirmation might be viewed by different constituencies.
In the cases of Sonia Sotomayor, Elena Kagan, and Merrick Garland, the Senate's considerations varied depending on the nominee and the political climate at the time of their nominations. Sotomayor and Kagan faced scrutiny over their liberal views and their potential impact on the Court's balance, while Garland faced opposition from Republicans who refused to consider his nomination during an election year. Ultimately, the Senate's votes on these nominees reflected a combination of these factors and the political dynamics of the time.