Senate: 50-50 Split?
If the Senate is split 50-50, who is in control? Has there ever been an even split?
If the voters in November choose to elect 50 Republicans and 50 Democrats to the U.S. Senate, Democrats would be considered the Majority because they are the party of the Vice President. (The two sitting Independents now in the Senate, Joseph Lieberman of Connecticut and Bernie Sanders of Vermont both caucus with the Democrats.)
The Vice President is named by the Constitution to be the President of the Senate [its presiding officer]. The Vice President would cast the tie-breaking votes on all the resolutions organizing the new Senate, including electing its officers and assigning committee seats.
The role of the Vice President, serving as the President of the Senate, is not just a symbolic one. A 50-50 would mean a greater number of tie votes. The Vice President would likely become a daily presence, because only he can break a tie by voting in the affirmative. He has the power to cast his vote in favor of a question, break the tie, and have it win. Because tie votes lose automatically, he would not have to vote in the negative, if he opposed the question.
In a 50-50 Senate, the Majority Leader would come from the same political party as that of the Vice-President. Although long a Senate tradition, the majority and minority Leader positions are not established by a vote or rule of the Senate. Each party in the Senate elects its own leader. The leader of the party which wins the majority is simply recognized by all as the Majority Leader of the Senate.
The last time the Senate split evenly was for a brief period in 2001. From January 3 to January 20, 2001, Democrats held the majority because Vice President Al Gore was a Democrat. However, on January 20, 2001, Republican Richard Cheney was sworn in as Vice President and became the Senate’s presiding officer, which made Republicans the majority party. Then, on May 24, 2001, Senator James Jeffords of Vermont announced he was switching parties - from Republican to Independent and that he would caucus with Democrats. That gave Democrats a one-seat advantage, and shifted control of the Senate from Republicans back to Democrats.
Senate parties have been at parity at other times due to Independents who chose to caucus with one side or the other.
In 1953, Robert Taft, a Republican of Ohio, was serving as Majority Leader, when he died. The Ohio Governor appointed a Democrat to fill out his term. That left the then-96 member Senate with 47 Republicans, 48 Democrats, and 1 Independent. The Independent, Wayne Morse of Oregon, agreed to caucus with the Republicans, bringing the Senate to 48-48. Republican Richard Nixon was the Vice-President, and therefore the Senate's presiding officer. That gave Republicans a fragile majority.
In 1881, the Senate stood at 37-37, with 2 Independents: one tended to vote with the Democrats and the other with the Republicans.