Even as same-sex marriage edges closer to becoming legal nationwide, gay rights advocates face other challenges in 2015 that may not bring quick victories.

In Congress, liberal Democrats plan to introduce comprehensive civil rights bills in the House and Senate that would outlaw a broad range of discrimination against lesbians, gays, bisexuals and transgender people. However, Republicans will control both chambers, and there's no sign yet that GOP leaders will help the bills advance.

Absent such a federal law, gay rights activists will seek to pass more nondiscrimination laws at the state and local levels, but some efforts are meeting resistance. A conservative-led coalition in Houston is trying to overturn a gay rights ordinance approved by the city council. A similar ordinance in Fayetteville, Arkansas, was repealed by voters on Dec. 10.