U.S. Vice President Joe Biden will deliver a speech at the annual convention of the Human Rights Campaign (HRC), the largest gay-rights group in the U.S., this week. The group advocates equal rights for gay, lesbian, bisexual and transgender people.

HRC, which had endorsed U.S. President Barack Obama for re-election in 2012, has already started attacking likely 2016 presidential candidates for their stance on gay rights issues, The Associated Press reported. Biden had spoken up for his support of gay marriage in a statement in 2012, calling the fight for gay rights “the civil rights issue of our day.” Biden's statement forced Obama's hand on the issue at the time, prompting the president to change his stance and speak up in favor of gay marriage.

Speculation surrounds the vice president's decision to run for president in 2016 elections. Biden had also participated in HRC's annual fundraiser event last year too, AP reported.

Currently, 12 states in the U.S. ban same-sex marriages. On Monday, a federal judge struck down a ban on same-sex marriages in Nebraska, a decision that could allow gay couples to marry in the state within a week.

"It is ordered that all relevant state officials are ordered to treat same-sex couples the same as different sex couples in the context of processing a marriage license or determining the rights, protections, obligations or benefits of marriage,” Senior U.S. District Judge Joseph F. Bataillon had said in Monday's decision.