In 2007, as his party—led by Governor Eliot Spitzer and Lt. Governor David Paterson—sought to pass same-sex marriage legislation, Díaz opposed the bill and was highly critical of Democratic support for it. Díaz's opposition to same-sex marriage continued in 2008, when he vowed to vote against same-sex marriage legislation and to withhold his support from any Senate Majority Leader who would allow the bill to become law. In May 2009, Díaz led a rally against same-sex marriage in front of the New York City office of Governor David Paterson; the rally was attended by an estimated 20,000 participants.