The U.S. Department of Justice and more than 300 companies have filed legal briefs at the Supreme Court in support of gay marriage.
Apple, Google, Johnson & Johnson and Goldman Sachs are some of the companies that joined the administration in asking the court to rule that states cannot ban gay marriage.
Hundreds of other groups and individuals also filed what are known as friend-of-the-court briefs, including religious groups, advocacy organizations and politicians. A gay rights organization, the Human Rights Campaign, delivered a brief with more than 200,000 signatures in support of nationwide gay marriage equality.
U.S. Vice President Joe Biden praised supporters of that group in Washington on Friday for their willingness to confront prejudice.
"Where there is courage, passion and commitment, there is opportunity. Where there is a willingness to directly confront prejudice, bigotry, homophobia, there is the ability to succeed. Because I believe after all these years, at their base, at their root, the American people want to do the right thing," he said.
The Supreme Court is due to hear oral arguments April 28 in four cases addressing state bans of gay marriage. Opponents of gay marriage are not due to file their friend-of-the-court briefs until later in March.
Gays can legally marry in 37 states, a major shift from just a decade ago. In 2003, no states permitted gay marriage. Massachusetts became the first to do so in 2004.