Mark Takano among Global Equality Caucus founding members
'We have a right to exist'
31 gay couples to marry in South Pacific country on August 19
Same-sex marriage bill received final approval on April 17.
Gays and lesbians can begin to marry in August
The measure passed by a 77-44 vote margin.
Measure's second reading to take place on March 13
Activists say it reaffirms administration’s commitment to LGBT rights.