Clinton's signing of DOMA and DADT have led critics like Andrew Sullivan to argue Clinton was a detriment to rather than an ally for the LGBT rights movement, though DOMA passed Congress with veto-proof majorities in the House and Senate. In December 1993, Clinton implemented a Department of Defense directive known as "Don't Ask, Don't Tell", which allowed gay men and women to serve in the armed services provided they kept their sexuality a secret, and forbade the military from inquiring about an individual's sexual orientation. The policy was developed as a compromise after Clinton's proposal to allow gays to serve openly in the military met with staunch opposition from prominent Congressional Republicans and Democrats, including Senators John McCain (R-AZ) and Sam Nunn (D-GA). According to David Mixner, Clinton's support for the compromise led to a heated dispute with Vice President Al Gore, who felt that "the President should lift the ban ... even though [his executive order] was sure to be overridden by the Congress". Some gay-rights advocates criticized Clinton for not going far enough and accused him of making his campaign promise to get votes and contributions. Their position was that Clinton should have integrated the military by executive order, noting that President Harry Truman used executive order to racially desegregate the armed forces. Clinton's defenders argue that an executive order might have prompted the Senate to write the exclusion of gays into law, potentially making it harder to integrate the military in the future. Later in his presidency, in 1999, Clinton criticized the way the policy was implemented, saying he did not think any serious person could say it was not "out of whack". On September 21, 1996, Clinton signed into law the Defense of Marriage Act (DOMA), which defines marriage for federal purposes as the legal union of one man and one woman, allowing individual states to refuse to recognize gay marriages performed in other states. Paul Yandura, speaking for the White House gay and lesbian liaison office, said that Clinton's signing of DOMA "was a political decision that they made at the time of a re-election." In defense of his actions, Clinton has said that DOMA was an attempt to "head off an attempt to send a constitutional amendment banning gay marriage to the states", a possibility he described as highly likely in the context of a "very reactionary Congress." Administration spokesman Richard Socarides said,