Booker is a strong, outspoken advocate of same-sex marriage and claimed New Jersey's civil union law was not only bigoted, but also discriminated against New Jersey's same-sex couples who were denied 1,100 federal rights, privileges and benefits afforded to married couples. After Governor Chris Christie vetoed a bill legalizing same-sex marriage in New Jersey and said the issue should be left to a public referendum of the people of New Jersey, Booker criticized him and said that civil rights are guaranteed by the US Constitution and should not be allowed on the ballot. As Newark Mayor, Booker refused to perform any marriage ceremonies until same-sex couples were legally allowed to marry in New Jersey. On October 21, 2013, 12:01 am, the date when same-sex marriage became legal in New Jersey, Booker began performing same-sex and opposite-sex marriages in New Jersey. In November 2013, Booker cosponsored and voted for the Employment Non-Discrimination Act. In January 2014, he cosponsored the Respect for Marriage Act. In 2017, Booker termed President Trump's military transgender ban 'deplorable and despicable.' In March 2019, when asked what he would do to protect LGBTQ rights as president, Booker replied, "When I am president of the United States, right away I will end this ridiculous, insulting, un-American ban on transgender Americans serving in the military." In October 2018, Booker was one of twenty senators to sign a letter to Secretary of State Mike Pompeo urging Pompeo to reverse the rolling back of a policy that granted visas to same-sex partners of LGBTQ diplomats who had unions which were not recognized by their home countries, writing that too many places around the world have seen LGBTQ individuals "subjected to discrimination and unspeakable violence, and receive little or no protection from the law or local authorities" and that the US refusing to let LGBTQ diplomats bring their partners to the US would be equivalent of America upholding "the discriminatory policies of many countries around the world." In June 2019, Booker was one of eighteen senators to sign a letter to Secretary of State Pompeo requesting an explanation of a decision by the State Department to not issue an official statement that year commemorating Pride Month nor issue the annual cable outlining activities for embassies commemorating Pride Month. They also questioned why the LGBTI special envoy position had remained vacant and asserted that "preventing the official flying of rainbow flags and limiting public messages celebrating Pride Month signals to the international community that the United States is abandoning the advancement of LGBTI rights as a foreign policy priority."