Supreme Court vacancies in presidential election years
In the wake of the death of Justice Antonin Scalia, questions have arisen about whether there is a standard practice of not nominating and confirming Supreme Court Justices during a presidential election year. The historical record does not reveal any instances since at least 1900 of the president failing to nominate and/or the Senate failing to confirm a nominee in a presidential election year because of the impending election. In that period, there were several nominations and confirmations of Justices during presidential election years.
The first nomination during an election year in the twentieth century came on March 13, 1912, when President William Taft (a Republican) nominated Mahlon Pitney to succeed John Marshall Harlan, who died on October 14, 1911. The Republican-controlled Senate confirmed Pitney on March 18, 1912, by a vote of fifty to twenty-six.
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In two instances in the twentieth century, presidents were not able to nominate and confirm a successor during an election year. But neither reflects a practice of leaving a seat open on the Supreme Court until after the election.
https://www.scotusblog.com/2016/02/supreme-court-vacancies-in-presidential-election-years/
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