New York State Senate

The New York State Senate is the upper house of the New York State Legislature, while the New York State Assembly is its lower house. Established in 1777 by the Constitution of New York, its members are elected to two-year terms with no term limits. There are 63 seats in the Senate. The Democratic Party has held control of the New York State Senate since 2019. The Senate majority leader is Andrea Stewart-Cousins.

The New York State Senate was dominated by the Republican Party for much of the 20th century. Between World War II and the turn of the 21st century, the Democratic Party only controlled the upper house for one year. The Democrats took control of the Senate following the 1964 elections; however, the Republicans quickly regained a Senate majority in special elections later that year. By 2018, the State Senate was the last Republican-controlled body in New York's government.

In the 2018 elections, Democrats gained eight Senate seats, taking control of the chamber from the Republicans. In the 2020 elections, Democrats won a total of 43 seats, while Republicans won 20; the election results gave Senate Democrats a veto-proof two-thirds supermajority. As of January 2025, the Democratic Party holds 41 seats in the Senate and the Republican Party holds 22 seats.

Democrats won 32 of 62 seats in New York's upper chamber in the 2008 general election on November 4, capturing the Senate majority for the first time in more than four decades.

However, a power struggle emerged before the new term began. Four Democratic senators — Rubén Díaz Sr. (Bronx), Carl Kruger (Brooklyn), Pedro Espada Jr. (Bronx), and Hiram Monserrate (Queens) — immediately refused to caucus with their party. The self-named "Gang of Four" refused to back Malcolm Smith (Queens) as the chamber's majority leader and sought concessions. Monserrate soon rejoined the caucus after reaching an agreement with Smith that reportedly included the chairmanship of the Consumer Affairs Committee. The remaining "Gang of Three" reached an initial compromise in early December that collapsed within a week, but was ultimately resolved with Smith becoming majority leader.

At the beginning of the 2009–2010 legislative session, there were 32 Democrats and 30 Republicans in the Senate. On June 8, 2009, then-Senators Hiram Monserrate and Pedro Espada Jr.—both Democrats—voted with the 30 Republican members to install Senate Republican Leader Dean Skelos (R-Rockville Centre) as the new majority leader of the Senate, replacing Democratic Senate Majority Leader Malcolm Smith. The Associated Press described the vote as a "parliamentary coup". The move came after Republican whip Tom Libous introduced a surprise resolution to vacate the chair and replace Smith as temporary president and majority leader. In an effort to stop the vote, Democratic whip Jeff Klein (Bronx) unilaterally moved to recess, and Smith had the lights and Internet cut off; however, they were unable to prevent the vote from being held. In accordance with a prearranged deal, Espada was elected temporary president and acting lieutenant governor while Skelos was elected majority leader.

Following the "coup", Senate Democrats voted for John Sampson (D-Brooklyn) to replace Smith as Democratic Leader. On June 14, Monserrate declared that he would once again caucus with the Democrats. This development meant that the Senate was evenly split, 31–31, between the Republican Conference and the Democratic Conference. Due to a vacancy in the office of the Lieutenant Governor, there was no way to break the deadlock.

Between June 8 and the end of the "coup" on July 9, the Senate did not conduct any official business. According to The New York Times, Espada's power play "threw the Senate into turmoil and hobbled the state government, making the body a national laughingstock as the feuding factions shouted and gaveled over each other in simultaneous legislative sessions." The "coup" also led to litigation.