Letter addressed to Majority Leader Chuck Schumer (D-N.Y.)
Lawmaker made history in 2018, becoming first bi member to serve in Senate
Bill passed with bipartisan support
Democrats now control U.S. Senate by 51-49 margin
Some advocates for religious liberty joined forces with LGBTQ groups to play a vital role in passage of the Respect for Marriage Act
Bill approved by 61-36 vote margin
Anti-LGBTQ groups have launched conservative effort to block bill
Bill advanced this week with Republican support
Final U.S. Senate vote could take place Thursday
Final vote could happen as early as Thursday
