Dean of the United States Senate

The Dean of the United States Senate is an informal term for the Senator with the longest continuous service, regardless of party affiliation. This is not an official position within the Senate, although customarily (since 1945) the longest-serving member of the majority party serves as President pro tempore.

The current Dean is Senator Patrick Leahy of Vermont.

For additional information here is a list of most senior Democratic and Republican Senators.

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