At the center of Republicans' opposition to President Obama's plans to nominate a replacement for Supreme Court Justice Antonin Scalia is the argument that the move has no historical precedent.
That's not entirely true — but the scenario is pretty rare.
The current situation — an opening on the high court during a presidential election year — has come up only a handful of times in modern history. Obama's particular circumstances — an outgoing president in his last year in office — are even more unusual.
However, that doesn't mean that it is customary to defer a nomination.
Reagan then nominated Anthony Kennedy. By then, Reagan was approaching his final year in office. The Senate unanimously approved Kennedy in February 1988.
After Scalia's death on Saturday, many Republicans vowed to block anyone Obama nominates to replace him. They assert that Obama's successor, who will be elected in November, ought to make the choice.
History, however, doesn't support that argument.
Since 1900, no president has chosen not to nominate a Supreme Court justice because of an impending election, according to an analysis by SCOTUSblog. And the Senate has little history of rejecting those late-term choices.
Here are some other relevant cases:
- President William Taft, a Republican running for re-election, nominated Mahlon Pickney in 1912, and the GOP-controlled Senate confirmed him. Taft lost the election later that year.
- In 1916, Democratic President Woodrow Wilson nominated Louis Brandeis and John Clark while running for re-election. The Democrat-controlled Senate confirmed both of them, and Wilson won another four years in office.
- GOP President Herbert Hoover, running for re-election in 1932, nominated Benjamin Cardozo, and the Republican-controlled Senate confirmed him. Hoover was voted out of office that year.
- In 1940, President Franklin Delano Roosevelt, a Democrat, nominated Frank Murphy, who was confirmed by the Democrat-controlled Senate. Roosevelt went on to win another term that year.
- President Dwight Eisenhower, running for re-election, nominated appointed William J. Brennan to the court while the Senate was in recess in late 1956. Eisenhower won the election, and Brennan was formally confirmed by the Senate the following year.
- President Lyndon Johnson, who had chosen not to seek re-election, nominated Abe Fortas, who was already an associate justice on the court, to become chief justice in 1968. In that case, the Senate blocked Fortas' promotion with a filibuster.
This article originally appeared on NBCNews.com.